Looking over the other shows.
Disco got its forum September 1 2016, over a year before it premiered. The show was first announced November 2015.
Picard got its forum November 26 2019, close to two months to the day before it premiered. The show was first announced summer 2018.
Lower Decks got its forum July 15 2020, just under three weeks before its premiere. The show was first announced October 2018.
Prodigy got its forum September 30 2021, just under a month before its premiere. The show was first announced February 2019.
SNW got its forum March 28 2022, about five weeks before its premiere. The show was first announced May 2020.
So there we have it. The furthest in advance we got a forum prior to a show release was Disco, at a little over a year. And as previously noted, at the time, we thought the show was going to premiere in January 2017, a little over four months in advance. Which would still be the soonest a forum was set up anyway. But even if you just look at the fact that Disco got its forum a year in advance, that means that since the Academy series isn't supposed to premiere until 2026, the soonest you can expect a forum is sometime in 2025. Even though like everything from Lower Decks onwards, it'll likely be a monthish before the premiere when we get the forum.