Fire Emblem: Fortune’s Weave has an irreversible cutoff at Act 3

You can replay chapters from the first act, so its deadlines do not permanently lock you out of recruiting characters.

Theodora’s path ends earlier than the others, on October 24.

The final cutoff comes when you start Act 3: after that, you cannot recruit new characters.

Check who is joining you before you pass through the Door of Destiny.