Wake him up at 7am. it'll be an awful day but he'll be ready for bed at a better time. We did it this summer with slightly older kids - took about 4 days for them to re-adjust but I found the only way to go was getting them up early! Oh, and fresh air and exercise late afternoon works a treat too!
I woke him early this am and shortened his afternoon nap but he is still swimgimg from the rafters. I know we will be back on track in a day or so but I feel like a zombie( we were at a 3 day wedding last wwekend over there so I haven't had more than 4 hours slep in a row for the last 6 nights) [tired emoticon]