Hi L. -
It is so hard for any of us to say what time is the right time b/c every baby is so different! I would judge the time she needs to go to bed based on how she acts, the amount of time she naps during the day, how easily she goes down at night and whether or not she stays asleep throughout the night.
My little guy is a horrible napper, so I have read a lot of books on sleep. It seems the general concensus is b/t 6-8pm for bedtime. I have many friends who's little ones do great with an 8pm bedtime and others (like mine) who can't make it past 6:30pm! The early bedtimes are awful for us parents, but I feel even worse keeping my little guy up b/c you can just see from his behavior and his eyes that he is exhausted!! I think it is b/c he doesn't nap well during the day (we have tried everything!)....so for now he has an early bedtime.
Take your cues from your daughter -- with a little trial and error, you will find the right bedtime for her (may not be so great for you!). If she has a really hard time settling at night, wakes frequently etc., she MAY need an earlier bedtime. If she is doing good with her current time, I wouldn't change it! I have heard adjusting bedtime by as little as 20 minutes can make a huge difference! And as they get older, they aren't always necessarily able to stay up later. When my son was taking 3 naps a day, he went to bed at 7:30. When he dropped down to 2 naps, it moved up to 6:30 or 7.....makes it really hard for us to go anywhere with him in the afternoon!
Good luck!