Don't know the mathematics or beast year hypothesizes, but there was a X-Mas sequel (with Tim Curry as the villain). In there I remember a sort of flask-back that does show Prince Adam refusing the enchantress's request. He looks to be between 10-13 years old in that flashback. Just pointing that out.

Too bad there's not a fully realized Comic Con Alaska (in the fall or winter months). He probably would have been much more comfortable.