It seems like a natural fit to have a big move on page 20, which is your slingshot into Act Two. It’s not a good use of your pages, however, to spend 20 pages developing a world that your character is going to abandon.
If this is your story, be extra diligent to set up your character in visual action in the first act, so that there is a clear sense of how this particular protagonist is going to run into conflict in the new setting.