Hi

There are a couple of common reasons he might be waking at that hour:
- hunger - have you tried feeding him and putting him back down? There can be a growth spurt around this age...
- first nap too early - though if he's genuinely waking at 6am and not napping til 9:45, then doing an UT nap as the EAS you posted suggests, I'm really confused. I suspect he's sleeping or at least not doing an awful lot of activity for a while/ in that time between 6 and 9:45.
This is a common age to be dropping the catnap and moving to 2x 1.5-2hr naps.
Usually I would say to bring the WU later by shifting your first nap later. I think that's reasonable in this case also, though I would caution that a 12hr night is not always a reasonable expectation from this age onwards and your boy may do more like an 11hr night more consistently. To shift the nap later, I tend to recommend that you do the nap after 3hr A time or a set time (say 10am initially), whichever is later to help encourage him to sleep longer in the morning. You then shift the set time later by 15mins every 3-5 days until you've got the first nap a suitable A time away from your ideal WU time. Does that make sense?
I'm imagining something like this being the final product, then as he gets older, the A times will increase gradually and BT would likely move later.
8 - WU
11 - nap
12:30 - wake
3:30 - nap
5 - wake
8 - BT