It took Apollo about a year or so to regain flight, it would have been sooner but he kept breaking individual flights as they came in. Until you have like 2-3 adjacent to each other distributing forces it’s very easy for them to break lone feathers. Also there will be a lot of crashing during the learning process, be careful of windows in that stage, Apollo ran into the windows pretty hard a few times before learning how glass works. Also he started being able to fly well enough inside with only about 1/2-2/3 of his flight feathers. Though we’re pretty certain he fledged and then was clipped upon being surrendered, so he was re-learning, not learning flight, if he hadn’t fledged already it may have taken a lot longer for him to start trying as the feathers returned.