The earliest we can expect the anime is winter 2026 and the latest is probably winter 2028, assuming you take the leaks at face value and assume Cygames is producing the anime.

How did I get to these numbers? Lets go over that real quick

So for the soonest we can expect the anime, it would have to A. be 12 episodes, B. have a production time of 1 year (relatively standard in the industry), and C. have started production the day of, or before the leak came out. If that was the case, it would mean production started in December 2024, and it would air in January 2026, a little over a year since production started.

For the longest wait it would have to A. have 23+ episodes, B. have a production time of 2.25 years, for a 2 cour show this is pretty good, above average amount of time for a show's production period, but not a completely impossible or unreasonable production period, especially if Shueisha wants the anime to look as good as possible. C. It would have to start production in fall of 2025. How did I get to this number? Well that's when all of Cygames Pictures' current projects end. Apocalypse Hotel should be done at the end of the spring season, even though it should probably already be done production already based on the news of Uma Musume: Cinderalla Gray's first cour. Uma Musume: Cinderella Gray should end at the end of the summer season, although cour 1 is reportedly already done production, meaning its second cour could be done around the end of the spring season as well. Finally, The Summer Hikaru Died should also be done by the end of the summer season, unless, like Uma Musume, its first cour is already completed production before airing, as it is a single cour show. This would only really happen if Cygames was specifically waiting for all their production lines to have completed their work to assemble a really big and experienced team for the Kagurabachi anime, which is probably unlikely. So based on that, 2.25 years from Fall 2025 would be Winter 2028.

Don't take this too seriously.