11h over night sleep is normal for your average child at this age. The range of normal would be 10-12h.
I would go for a 7.30pm start of bedtime routine, asleep by 8pm at the latest, for a 6.30-7am wake up.
But you can't just change bedtime, just like that. It won't work, because baby will be exhausted and over tired.
You may need to make a temporary change to daytime sleep routine, in order to effect that change. That might either mean having longer naps at different times, if you were previously waking from naps and limiting nap lengths. Or it might involve making naps earlier do so that you can add in a third nap. These changes are not perminant, just to allow for moving bedtime. Then give it a week or two to establish and move back to the routine you have, just with a different bed time.
Some possible examples (there are loads of other options):
Wake 5.30am
2h30m awake time
Nap 8am, leave to sleep as long as possible. Say 90m, waking at 9.30am
2h 30m awake time
11.30am nap for as long as possible. Say 2h until 1.30pm
2h30m awake time
4pm power Nap. Wake up at 4.45pm
3h-3h30m awake time
7.30-8pm bedtime
Or
5.30am wake
2h awake time
7.30 nap as long as possible. But say thing nap is only 45m until 8.15am
2h awake time
10.15am nap as long as possible. Say until 12.15pm
3h awake time
3.15pm waking up after 45m
4h awake time
8pm bedtime
Or
5.30 wake
2h awake time
7.30-8.30
3h awake time
11.30-1.30 nap
3h awake time
4.30-5.30 nap
3h awake time
8.30pm bedtime
Or
5.30am wake
3h awake time
8.30-9.30 nap
3h30m awake time
1.30 - 3.30 nap
4h awake time
7.30pm bed
There's loads of other ways to do it. The idea is that by allowing extra daytime sleep and timing naps differently, baby can go to bed later without being exhausted.