I don't know about WL specifically, but a couple of years ago we arrived at CSR on Christmas day . We noticed that they began to take a few things down around "the world" the very next day! Granted, there were still plenty of decorations to see over the next few days of our stay (we left New Years eve "day", but we were disappoined they started so quickly after "the day" ) So from our limited experience, I would say most if not all decorations would probably be gone by that date!