Last year on Friday, November 10, which was the first day "holiday it's a small world" opened, and the first night of the "Believe...in Holiday Magic" fireworks, the park was at capacity for several hours in the afternoon (they didn't allow anyone to enter), and by 2:00 they had stopped selling single day passes. It was really crowded. It wasn't nearly so bad the next week, and I think the Christmas Parade started the following weekend. As I recall, everything except the Christmas parade was up and operating by the 11th - I think Santa's Beach Blast at DCA and Santa's Reindeer Roundup at DL opened ~November 6.