Do the birds start a chirping around this time? Sometimes these 'outside' noises cue them that is morning!
That or there is also a 18mth sleep regression I think...Ill see if I can find the link, though I am unsure if this is to do with napping/BT or EW (or all three)
If he is waking happy from his nap after 1 hr it could be he needs a touch more A time before his nap, or to BT and that he is UT.
What time does he take his nap usually?
Sounds like he is a happy toddler which is lovely. We had EW for a while and they are tough on you more than anything.