I used to know a guy who swore it went up a WL between Nov 16-17 every year, but I've seen other people's TRs that debunk this theory. That being said, I was at YC one year and we went to bed on the 16th with no decor and woke up to full on Christmas the morning of the 17th. All of the gingerbread was in progress before this though. In fact, we went a little earlier one year and I think it was either Nov 11th or 12th when we saw the first piece of gingerbread going on the GFs house and the early progress on the Contemporary gingerbread...although, no other resort stuff at that point.