My daughter never goes back to sleep on early flights- she does on afternoon flights, but like Eclipse Pearl I have seen many kids melt down then. My recommendation would be to book a flight at a time that you, as parents, would most likely be well rested, so that you can best and most patiently deal with whatever transpires.

Then, I would recommend that you bring activities that your son enjoys- multiple activities in case he tires of them- like 5-10 different things or more. If you can tame him with the electronic hypnotist consider purchasing a DVD player or loading movies onto an ipod video. With many kids, that can buy you hours of peace.

My worst trips with my daughter have been when I am too tired to cope myself. No matter how badly it goes, if I am well rested then I can deal with it. For me, the 6:30 am flight wouldn't work. I would be too tired.