December 21st is a Tuesday, not a Sunday. Sunday the 19th and Tuesday the 21st are the last 2 days of the Disney Very Merriest After Hours, so if you're not planning on going to that, I would go to Magic Kingdom the opposite day, 20th or 22nd and go to Epcot on the 19th or 21st, however that works out for you.We are heading down in December. Epcot and Magic Kingdom, will it make any difference which park on which day, Sunday the 21st or Monday the 22nd? Yes I know it will be busy but those days or no days.