12 month old sleeping 8-9 hours total a day

She sleeps about 8 hours at night and only about an hour of napping in the day. I need to bring her bedtime earlier.

She’s transitioning to 1 nap, so she will go to bed sooner if it’s a 1 nap day. If it’s a 2 nap day she’s up a lot later. If she takes 2 naps, she wakes up from her last nap tired and unhappy for a long time, but she won’t go back to sleep, even if I rock or nurse her. She’s obviously tired though so makes me think she needs to go to bed sooner than she is. She wakes up a lot in the night again too which I’ve heard is a sign of an overtired baby

So what time should my 12 month old go to bed?