They're a little unhinged but it's ok
So a clearer timeline for this au (bc I can't stop thinking about them):
Sokka started joining the Southern Water Tribe to trade with Kyoshi village when he was around 6 years old (originally because Kya had her arms very full with two hyperactive children so Hakoda decided to take Sokka on an "educational field trip" instead of just leaving his wife and mom to deal with the kids.)
He and Suki did NOT get along but Hakoda did notice that Sokka seemed to really enjoy learning about Kyoshi's very different culture so it became a thing-- twice a year, Sokka would join the traders up to Kyoshi
Katara started joining those trips when she turned 6, but after Kya's death, Hakoda decided that it wasn't safe to risk Katara's safety by bringing her to foreign lands, even if Kyoshi village likely weren't the ones to inform the Fire Nation that there was still a waterbender in the Southern Tribe
Suki and Sokka start getting along when he's 8 and she's 9-- Suki starts training to become a Kyoshi Warrior and Sokka ends up swallowing his pride and asking her to teach him some moves.
They get especially close after Kya's death-- Suki is the only one Sokka actually opens up to about his grief.
Sokka stops visiting Kyoshi village after his 14th birthday, when the Southern Water Tribe's warriors leave with all of the ships. He doesn't get to tell her why he never came back.
She 100% punches Sokka in the face when he comes back, aged 16, hauling the Avatar with him. Then they hug :)