I'm in the middle of this situation too. My ds used to have an Awake time of 6 hours before nap1 and 5 hours before bedtime and was working quite well. On days i let him nap for longer he was ok to be put down for bedtime at 4:30 or 4:45 hours of awake time but this past week he's just not tired by then. He sings and crawls and plays in the dark for 30-45 mins... or wants us to be in the room playing with him!!!!!!!
I'm trying to move nap back in 15 mins increments each week. So far, i've been putting him down at 5:45 awake time for nap and then that makes him go to bed at 5:15 awake time. He's been doing better, taking 15 mins to settle to sleep. I'll keep doing this for a week more and then move back another 15 mins so we end up in a 5:30 awake time for both periods which is my goal.
I must say that my plan B was getting used to that super late bedtime. I had set my mind into it just in case my main plan does not work.
I beleive that bedtime is a timing that works for you. So if you, your household, dh and dd are ok with 830, then that would be a great bedtime no matter what everyone thinks about it.
HTH! i'll let you know how it works for me!