My son is now 20 months old and goes to bed between 7 and 7:30 p.m. That's when he's tired, and he has been going to bed then for more than a year now (since he was on a more regular sleep and nap schedule).
He takes one nap a day now, goes to bed around 7ish, and wakes up around 6:30 a.m. Some kids even his age do about the same, and some are more late night kids with different schedules -- we have a morning guy!
We just always did what seemed to work for our little guy, as it makes our life easier when he's rested, in a good mood and able to have some control over his routine.
Yes, this can be challenging sometimes with evening plans (especially if we get invited over somewhere and folks want us to bring our son and don't understand why he needs to go to sleep earlier than 10 p.m.)!
But, I know he'll only be this little once, he needs his sleep, and my hubby and I enjoy our time as adults in between when he goes to sleep and when we do.
We remember the days when he was a small infant and we would take him places and he'd stay up until 10 or 11 p.m. But, we actually prefer now just because he sleeps through the night, is much more on a real schedule, and we know things can change anytime! ;)
We've just had to let friends and family know what works for our family to see our son (weekends, early evening, daytime) and realize that this to shall pass! ;)