There doesn't seem to be a set date when things come down. I've been to WDW about 5 times during that very first week in January, and seeing Xmas decorations has really varied. One year, when checking out of POR to go home on 1/8, the decorations were still up there. However, one year I went to Epcot on 1/2, saw the tree, then 2 days later I went back and it was gone and replanted. Another year, that same Epcot tree was up until 1/5. The one thing I have noticed, however, is that when the decorations come down, the whole thing is done overnight, nothing is left "partially" done. DS and I saw the Epcot tree one afternoon, then the next morning, we went back and not only was the tree gone, but the area was all replanted like the tree had never been there. Boy, those Elves work fast!