Has the big AM nap come earlier b/c he was waking early or has it always started at 9.30am?
If it has always started at 9.30, then I think the reason your WU is early is b/c of that big nap being at that time. Having a too long and/or too early morning nap can actually encourage early waking, b/c they are able to finish off their night sleep during the morning nap. And chances are, if the nap was at that time when he was going to bed at 7-8pm then he was probably OT at bedtime hence why you still got the EW even with the later BT. Atm at least by having an earlier bedtime he is getting a better night's sleep IYSWIM?
Right as for what to do from here: the thing with this transition is that for some it is quick, for others it can take months & months. You might find he keeps his current 2hrAM nap & 45min PM nap for a month or 2 before you need to cut things back more. Or in a week or 2 he might be ready for change. So waiting it out is entirely up to you but be prepared that it *may* take a wee while. IIWM I would still push the nap back whilst you are transitioning, rather than waiting til its complete. My reason is this: If you continue to put him down at 9.30am for his big nap & gradually phase out the PM nap, he will end up doing a VERY long A time to BT and this will only serve to make him OT, and its likely your wakeup will get even earlier, and then you'll have a very big job on your hands to get everything shifted out later.
This is b/c its pretty much what happened to us when my LO transitioned. We started with 5am EW so our first 1 nap days were 10am-12pm, and he was horrifically tired by 6pm BT (the latest he could make it to) & we had multiple NW's every night & the early starts continued b/c we were stuck in an early nap, early bedtime, early wake cycle. So I have total sympathy & want to save you the awful trouble we had!! It took us a very long time to get our nap shifted later b/c he was always OT from the long stretch to BT, and he is now (at 17months) finally napping after lunch & we are having much better WU's as a result.
So what I would do is over the next few weeks put him down 15mins later each week for his AM nap & let him sleep. And work on getting that nap towards 11/11.30am. As that PM nap heads closer to tea-time, you could try cutting it to 30mins & see how he fares with that. Then you are still gradually working towards your goal of dropping the CN & having one big nap over lunchtime.
HTH.x