Arcane timeline for season 1, acts 2 and 3.
The reason for my focus on acts two and three specifically is because this was motivated by reading one too many fanfics that stretch out Jayce being absorbed by council business while Viktor was alone in the lab into a status quo lasting months. I wanted to prove how short Jayce's career really was.
Putting together a timeline for Arcane has been interesting largely in how coherent it is. Making a timeline for something you love often results in it falling to pieces in your hands, but Arcane is built meticulously. There are a few seams, but very few.
Day 1
This is Progress Day and we can tell it all happens on Progress day because we get to see the ongoing festivities in between more important events.
It's sunrise when Heimerdinger tells Jayce that he wants him to do the speech and asks if he has anything to show. Heimerdinger does say this is short notice, but it's really short notice. Jayce also has to spend the morning meeting people with Cassandra, which may mean that putting together their showcase for Heimerdinger mostly fell on Viktor.
The morning is also when the Firelight raid on an airship docked at the hexgates happens.
In the afternoon Heimerdinger attends Jayce and Viktor's showcase but tells them they need more time.
Caitlyn, meanwhile, leaves her post outside her parents' tent and sneaks into the airship that was raided earlier to examine the crime scene.
At sunset Jayce goes to talk to Mel. This must be shortly before he gives his speech because it seems like talking to her has nearly made him late for said speech.
It's after dark during the speech and Caitlyn's "graveyard shift" has started. Shortly after the end of the speech Jinx blows up a building as a distraction while she steals the gemstone and Caitlyn is caught in the blast.
Day 2
Mel makes Jayce a councillor.
Silco has learned what Jinx has done but when he goes to yell at her for it she gives him the gemstone.
Jayce visits Caitlyn to check she’s okay, show off about becoming a councillor, and try to offer her a job. Also it seems to have been left to him to break the news she’s lost her job as an enforcer.
At or soon after sunset Caitlyn goes to Still Water looking for Gustove and meets Vi, forging Jayce’s signature to get her released.
Day 3
Viktor and Jayce are overseeing work on securing the hexgates. Jayce has already read several months worth of shipping manifests in his effort to root out smuggling. He tells Marcus to search and seize any unauthorised merchandise and gives him a list of suspicious transactions.
Marcus says it's Jayce's first day on the job and accepts it when Jayce corrects him to second, which would make my designation of this as day three very solid. Jayce does also reference "yesterday's smuggling fiasco" but I think it's more likely he'd misspeak about that than that he and Marcus would both be wrong about when he was made a councillor.
This is also when Viktor has a vision of, presumably, the hexcore, since he later says he saw it in a vision.
Day 4
This is the only place where I can't be sure about the timeline. This could still be Day 3 and there's an outside chance it could be Day 5 or 6.
Later on this day (at the concert) Amara will say she had enforcers at her door that morning. This would be more likely if there's been a day in between Jayce giving Marcus the suspicious transactions and the concert. This also gives Viktor a whole day to build the hexcore rather than six to eight hours.
On the other hand it means that Caitlyn released Vi from Still Water at night and it wasn't the next day but the day after when they headed into the Undercity.
Since there's not anything actively ongoing (no one is wounded, on their way somewhere etc.) this is also a place where you could insert a longer timeskip as long as you can explain where Vi and Caitlyn were. I don't think it could be more than a few days, but it could exist.
I'm assuming it's Day 4 for now.
Vi and Caitlyn spend the day in the Undercity, arriving at Babette's brothel in the evening where Vi is given information about where to find Sevika and ditches Caitlyn to go after her.
Meanwhile, Jayce stops by the lab, but it seems like he hasn't been there long and he's getting ready for the concert while he's there. He doesn't really understand the theory behind the hexcore and doesn't have time to have Viktor explain it thoroughly. Which is a shame, because he really ought to be more worried about Viktor building something that the arcane can act freely through due to seeing it in a vision.
Many important events happen at night. Viktor collapses in the lab and exposes the hexcore to blood in the process. Jayce is corrupted by backroom dealing and then has sex with Mel. Jinx undergoes a baptism at Silco's hands in an attempt to "kill" Powder.
It appears to still be night rather than the morning after when Jayce talks to Viktor in the hospital. In fact, it seems like not much time can have passed at all since Vi is still on her way to find Sevika at a location she was given by Babette.
Vi finds and fights Sevika and is wounded in the process. Meanwhile Jinx gets hextech working.
Day 5
Jayce goes to Mel for comfort, and possibly to deal with his own feelings about Viktor's death with someone other than Viktor. This might be a time when it would have been better if he'd been with Viktor, though, since this seems simultaneous to Viktor touching the hexcore which... seems to do something to him, since his eyes roll back in his head afterwards.
I think the next events must happen simulataneously, because Vi's wound does not get treated until the end of the sequence. Not even staunched besides her having her arm over it.
Jinx tortures Sevika in Silco's study (using the Grey to knock her out, or at least something animated the same way as the Grey).
Meanwhile, the reason Silco isn't in his study is because he's threatening Marco's daughter.
Meanwhile, Viktor shows Jayce the tests he's running on plants, giving them both hope for a cure for Viktor. Despite the fact he's been aware the hexcore interacts with biological matter for less than a day, Viktor seems to already be despairing of figuring this out in the time he has left. We never learn the answer to how much time the doctors' said Viktor had left although we heard him ask the question, and that may be one of the few places Arcane fudges things, because it's hard to imagine an answer that both sounds like a prognosis doctors could give and justifies Viktor acting like not being able to figure something out in a few hours is a crisis. My best guess is that he's either essentially been told he could die any moment, or he is actually panicking and this isn't rational. Jayce suggests they ask Heimerdinger for help and in the meantime helps Viktor with the equations.
Meanwhile, Caitlyn and Vi go to Vi's old house in the fissures in search of somewhere safe to rest. Once they reach it Caitlyn does her best to staunch Vi's wound.
When Heimerdinger sees the hexcore he demands they destroy it. He also says Viktor has changed - apparently since Heimerdinger talked to him that morning. Possibly this is related to his reaction when he touched the hexcore. Viktor probably leaves Piltover to look for Singed immediately after this, he's crossed the bridge before the blockade goes up.
Caitlyn meets Huck and trades with the healer for something that could help Vi.
Heimerdinger calls the council meeting at which Jayce coups him and throws him off the council. While waiting for this meeting Jayce talks to Marcus, is given the grenade, and orders the blockade on the bridge.
That night, Silco attacks Vi after Huck sells her out for Shimmer. Vi and Caitlyn escape from him just in time for Vi to follow the beacon Jinx has lit and reunite with her. The Firelights attack and carry off Vi and Caitlyn.
Day 6
Singed gives Viktor shimmer. Meanwhile, Jayce is in the forge trying to avoid his new job as head of the council. He's tried to take the grenade apart but failed. He's worried about Viktor and also about Caitlyn, since he's recently discovered she forged his signature to release a prisoner.
Vi is released by Ekko and spends the day being shown around the Firelight commune.
Viktor is caught in the blockade on his way back across the bridge and decides not to tell Jayce about the shimmer.
At sunset Mel receives a letter from Ambessa, possibly announcing her arrival in a few days (although if so I wonder why Mel brings weapons up to Jayce afterwards when otherwise Ambessa's presence makes her turn against the idea of weapons).
Day 7
The Firelights free Caitlyn who has presumably been tied up for the whole of Day 6. Caitlyn convinces Ekko to return the gemstone and take a chance at making peace with Piltover.
Jinx returns to Silco who hasn't seen her since Day 4 or maybe the morning of Day 5.
Viktor takes the grenade apart. Mel suggests hextech weapons. Both Viktor and Jayce are distressed by the idea, but Jayce is persuadable and Viktor is not.
At night, Viktor uses shimmer and the hexcore to heal his leg. He does not immediately test it out - we have no idea where he is between now and the evening of Day 8, which might imply shimmer side-effects he's hiding. (Jayce doesn't seem to look for him either although he does start the day with a new emergency to deal with.)
The massacre on the bridge happens. The enforcers try to stop Vi and Ekko returning to Piltover and then Jinx kills everyone.
Day 8
Jayce and Mel see the corpses on the bridge.
Caitlyn takes Vi back to her house. Despite her reservations, Cassandra schedules an audience with the council for them. (Cassandra intrigues me. She seems like an obstructive snob and then you get moments like this and the fact that it seems like she might have been behind the vents. That's more than a lot of Topsiders care.)
Jinx spends what seems to be much of the day being treated by Singed.
Heimerdinger, who left shortly before the blockade went up, returns to Piltover and meets Ekko.
Ambessa arrives. She argues with Mel about weaponising hextech, then later meets Jayce and manipulates him.
In the evening, Caitlyn and Vi talk to the council, trying to convince them to move against Silco. Jayce offers hextech weapons to do so, but Mel wants to avoid war.
That night Jayce, frustrated with the council, goes to the forge and immediately makes the hammer. He is convinced by Vi to raid a shimmer factory with her to shut down Silco's operations.
Meanwhile, Viktor tests out his leg then immediately goes back to continue his transformation leading to Sky's death.
Jayce raids the shimmer factory, killing a child. Viktor tries and fails to destroy the hexcore. Jinx kidnaps Caitlyn.
Day 9
Mel learns about the raid and fights with Ambessa about Ambessa corrupting Jayce.
Viktor scatters Sky's ashes and considers suicide but is interrupted by Jayce. The two of them resolve to make things right.
In the wake of an attempted coup by the chembarons Silco receives a message from Jayce.
Day 10
Silco and Jayce parley at sunrise.
Heimerdinger and Ekko reach Ekko's commune after setting out on Day 8.
Jinx overhears Silco talking to Vander's statue and believes he might be considering betraying her.
Vi fights Sevika at the Last Drop and wins, but is kidnapped by Jinx.
That evening Jayce pushes for Zaun's independence and nearly succeeds. Meanwhile, Jinx holds her tea party and, after killing Silco, fires her hextech weapon at the council.
So, 10 days, although I suppose I'm only definite it's 9-12 days.
I did come out of this feeling that, yes, Jayce should have been paying more attention to Viktor. But also, Jayce had to deal with multiple emergencies over a little more than a week while doing a job that could get people killed if he messed up.
