What they said.
When we went 8 years ago, we were there a couple days before (not bad), during (went to other attractions in the area when it got too crowded, Universal, Kennedy), and after. It was AMAZING to see the overnight transformation of the park into a winter wonderland.
Spent Thanksgiving evening in the ER as my DS (6 at the time) got dehydrated. That was also an Epcot day, so a long day, unseasonably warm, and refusal to continue pumping the liquids = not a good combination.
Enjoy!!!