It looks like that the naps are a little short and you need to work on making them a little longer, he could be overtired going down for them as he is awake so early. You seem to be in a bit of a vicious circle as you can't let him nap earlier and because of that he has problems night sleeping which makes him wake too early, then he gets his nap too late and so on.
You need to try to get him to stay a little longer in the morning. Try wake to sleep in the early morning.
Let me know how you get along, A nap at lunch time is fine, but as I say, it should be a little longer, about 2 hours minimum, and I think that this will happen when you can get him to sleep longer in the morning. When you can get this routine going then I think that you can start teaching him to fall asleep on his own.
In my experiences of my own since turning 1 year old(Alex and Childminding LO) it works for us for them to wake and be awake for 5 hours, sleep for 2-2.5 hours then wake for 5 hours, then sleep again at bed time. I try to keep to this routine as much as possible.