Regarding your tags mentioning how long since s02e09 Autoboot Camp, we actually have two different sources to infer a general—if incredibly broad—time span.
Starting with our most trusty worthy source of information, we have Optimus Prime. In s03e12, Endgame Pt. 1, Optimus recalls conveniently enough a series of flashbacks that showcase his own personal timeline from the incident of Elita-1’s abandonment as cadets to present day. During the portion where Ratchet accidentally blows up Prowls ship, leaving him potentially stranded, Optimus says our first indicator of a timespan with, “Easy, we can transport you once we’re finished in this sector. Shouldn’t be long—fifty or sixty stellar cycles, tops.”
Given both the longevity of Cybertronians plus Optimus’ laidback attitude regarding it, I think it’s reasonable to assume it’s been some sort of amount PLUS the 50 year stasis period that sets off the chain of events on Earth in the show. But that could mean anywhere from one year, maybe two years, or fifteen. So that brings me to my second source of spanning time:
Love him or hate him he actually gives a much broader number to work with regarding the potential timeline. During the airing of the show between the release of season 2 and 3, a series of comics were produced. The events in The Arrival are generally canon-compliant (or at least, canon noncontradictory) so we can infer that as supplemental material we can somewhat trust the information as being relevant to the actual canon of the show itself.
Now the comic First (and Second) in Flight was one of these supplemental comics made during this time that was specifically released as an exclusive feature in the Jetfire + Jetstorm toy set. It tells the story of the accident that led to the two of them being experimented on with Starscream’s coding to create flying Autobots. The comic is set in-between the events of season 2 present-time, as such this panel is particularly interesting:
The context specifically is that Sentinel is assigning new names to the twins, much like he did in Autoboot Camp. Since that was the only other instance where we witnessed Sentinel actively name other Autobot cadets, we can infer it’s been thousands of years since Wasp was wrongfully imprisoned.
A couple of roadblocks in all of the above:
If we take Optimus’ timeline as concrete then the events of the show are reallllly squished together. There’s an unspoken overlap going on that would have the audience believe that at the same time that Bumblebee enters bootcamp, Optimus fails in going back for Elita-1 as Bumblebee and Bulkhead BOTH are present as repair bots when Optimus is assigned captain of the ship. At the very least, events of Autoboot camp happen simultaneously as the investigation into her death and the nebulous time in-between Optimus getting assigned captain. Personally, I don’t think there’s much credence to believe that any significant amount of time between being removed from the academy and getting pity-promoted occurs.
I find the concept that everything happens on top of each other really funny but also strangely quick-paced for the show, but it’s what we have to go off of so what can you do.
Onto our longest source of information: Sentinel. We would have to take Sentinel at his word when we know that he’s generally a character who we’re not supposed to trust at face value. I’m willing to give him the benefit of the doubt here because he doesn’t really gain much from specifying how long it’s been to Jetfire and Jetfire (now Jetstorm). As a braggart, if he was trying to cover up how long it’s been one would expect him to go higher not lower and consistently throughout the show we see examples of bots throwing out large numbers of cycles to emphasize the difference in lifespan between us and them. For all we know, “a few thousand stellar cycles” could be equivalent to just “a few years” on a human-scale of interpreting time.
This information also comes from supplementary material that while yes, produced both during the production/airing of the show AND written by the crew (Eric Siebenaler and Marty Isenburg specifically), I’ve always been an advocate for the side of, “If it’s not in the show itself the information can be discounted.” Personally again, the canon-compliant nature of these particular comics has my favor.
So with all of that out of the way, I think it would be fair to say that it’s been at the very least 1000+ years since Wasp was imprisoned in the Cyber Stockades.
A note: idgaf if the Complete Allspark Almanac has contradicting information as that is a perfect example of me invoking the Discount-Supplementary-Information clause.