STM: Late bedtime for 6.5 month old?

Curious if any mamas went against advice and had better luck with a later bedtime for older babies?

Background: Prior to 4 months old, my baby went to sleep at around 9:30/10. He would fall asleep on the sofa with us first around 9, and then I’d bring him up, he’d briefly wake up, and I would put him back down to sleep around 930/10pm. He slept great then! 8-10 hour stretches.

Since turning 4.5 months, I tried to get him on a better schedule and started putting him down around 8/830. Around that time he started waking up an hour after bedtime, and every 1-2 hours all night long, sometimes giving me one 3 hour stretch in the beginning of the night if I was lucky. It’s been 2 months of misery! I thought it was just the 4 month sleep regression turned into a poor sleeper.

Last night, I put him down at 9:45pm because we were out to dinner and got home late, and he slept 7 hours straight!!!

Would love to hear any similar experiences from other mamas.