I totally agree that an earlier bedtime would have been better! I was aiming for 7pm but he just doesn't flag - so it's so hard to judge!
Last night he also woke at around 10pm and I just went in and said "go back to sleep" and he did immediately - so earlier wake ups don't require me to lay/stay with him, but when he wakes later on he is wide awake... He cries/shouts over & over & over and won't let me leave, he begs for cuddles and just wakes further up if i don't stay. Because he is LSN once he has had a few hours it is much, much harder for him to go back to sleep, that's also why even cat naps cause such issues!
We tried a gro-clock but as I won't leave him to cry alone (& going in & telling him to go to sleep & leaving makes him hysterical! He just gets out of bed and follows me!) I just ended up in his room with him until it lit up - it was pointless! When he wakes, especially later in the early hours, when he struggles to go back to sleep, he just wants me & is far likelier to go back to sleep with me there than not.
I don't think anything other than his routine is responsible for the wakings. His balance of day/night is a very fine line for him to sleep well, but he's shown loads of times he can STTN no problem when it's right. I honestly don't think he has prop issues, although I can see it might look like that. He STTN for months with no intervention from me - it's only since the 0-1 took hold I've had to lie with him.