Thats right, if he's overtired, the later bedtime is not a good idea. So I would do an earlier bedtime (say 6-6.30pm) for about 3-4 days to give him time to catch up on sleep. Keep the morning nap at 9am, so if he's doing a 9am nap (wake him at 45mins) and the pm nap around 1-1.30pm and bedtime 6.30pm. Once his wake up time is around 6ish then you should be able to push the morning nap further to say 9.30, pm nap to 2pm and bedtime around 7pm. I would wait about 3-4 days to see results.....