Book your fastpasses and then after those just stroll around Epcot. On my CP I somehow ended up with Christmas off and I had a fantastic time there. My friend and I walked around the World Showcase stopping at all of the storytellers that were still meeting. I think the Santa in American Adventure is the only one who leaves to preserve the magic for little ones who still believe in Santa. Besides that there will be some food kiosk and special offerings. If Japan has their holiday sake shots again beware! That was one of 2 times I have ever been drunk in the world and the flight of shots was all I had. They were so good and tasted like melted jolly ranchers. The alcohol content was deceptive haha.
I would come at opening and hit Future World, put your fastpasses mid day so you can really maximize opening especially with families who are either just arriving not yet there yet or those who are there still back at the resort opening gifts. Get your FP for the noon-3 tiem frame and use those then head back to World Showcase to enjoy.