I was never able to find one online. Apparently it changes daily.
When we were there in June, we spent a morning on Main Street meeting characters at the town square. The character handler/coordinator (not sure the official term) has a clipboard with a schedule and, if you ask politely, he or she may tell you when characters will be out and where to find them.
We probably met 10 characters in the course of 1 1/2 hours.