Act II begins after the inciting incident, and about the time that they approach the crossing of the threshold, that is, crossing into their new world. The new world doesn’t literally have to be a new magical world, but that which takes them out of their daily usuals.
or the most part, the first part of Act II is your MC responding to the Inciting Incident. It’s them getting their footing and trying to navigate the new world or reality they’re in. However, at some point they have to take control of the reigns and work toward the problem, rather than simply responding to it.