The tree should be definitely up by then. We stayed at WL in November 10-17, 2001. We had actually had hoped to avoid the Christmas decorations--our previous 2 trips were at Christmas time. Wednesday night, and I do mean LATE night, they decorated outside and erected the tree. It is very impressive. And they did it overnight--if we didn't stay out late that night we would have had a HUGE surprise when we woke up.
Have fun!