I believe that two years ago, they did change the MK opening time on Thanksgiving Day from 8:00 to 7:00. We had an 8:30 breakfast ADR at CRT, so that worked out perfectly. We rode TONS of stuff in that first hour and a half! I think it was a fairly last-minute announcement, though. And I don't remember opening times changing any other day that week--but I could be wrong about that.