Wow, sounds promising! I agree that 4 hrs is probably a bit too much. I think he should be ok on one long and one shorter nap with 6.30pm bedtime and at 8 months we were doing 45mins-1hr morning nap and a longer afternoon nap about 3hrs later with bedtime around 3-3.5hrs later. So, I think if you can manage to keep him awake until 9.30am in the morning and do the routine you posted, hopefully his day will shift later too and without that 3rd nap, which can interfere with night sleep, he should hopefully sleep better at night!