Can I bake apple crumble ahead of time?

A&M are right, but consider to add a small scoop of ricotta on top when serving.

You can, but you'll want to make sure you can reheat it just before serving so that the filling is warm, and the crumble crisps up again.

Yes, you can. You can also eat it at room temp, but if you'd prefer to serve it warm, bake it now, and then reheat it in a 200 F oven to serve.