Hmmm these bubbas are ganging up on us! There's been at least 2 other threads around about this in the past week, and my DD has started waking early too... methinks their little bodies are waking up from 'winter mode' and getting up earlier with the sun (although your little guy is beating the sun by a fair bit)! Chinese medicine has held for centuries that our bodies cycle with the seasons and we need different amounts of sleep, have different dietary, work and energy patterns depending on the time of year. I think we as adults tend to 'tune out' of our bodies natural cycles, but our little ones are far more sensitive. Spring is in the air... it's just hard to feel it when you've been up since 4:30am!

My DD is a little older and I can fairly easily get her to have one sleep or 2, just depending on our routine. At least for us, number or length of naps makes no difference to her wake up time at all. Same as you... late night or early one, big day or quiet one.
She went through a phase like this at about 12 months (again coming in to a change of season) and I had some limited success with
- not giving her a big brekkie until 7:30 so that her body was not waking up 'expecting' food 'till then. If she asked I'd just give her BM or a little bit of toast / cracker.
- sometimes if I brought her into bed and completely ignored her (pretended to be asleep) she'd just play for an hour and go back to sleep. This only worked occasionally and more often resulted in me getting up as i was sick of getting a finger up my nose or my head sat on, but the few times it did work, she'd go back to sleep for at least 2 hours - convincing me that she definitely needed a longer sleep overnight. She however was not convinced... until a few weeks into Winter really set in and she decided to start sleeping 12.5 - 14 hours overnight (often not getting up 'till 8:30 and occasionally 9).

Good luck! Hope you get some more ZzzzZzzs soon.