Tether it depends on the regional culture, as so much does. DH was 27 and I was 24 when we married in 2006; I'm not sure if that's "young" or not but it wasn't seen as all that unusual to anyone where we live. We had our first DC nine months and 4 days later, right after I'd turned 25, and again didn't feel young.
My uncle lives in Mnahattan and is very of that culture now. He was married at 40 and he and his wife have one DD, who is a year older than my DS. He remarks on my getting married and having children so young often.
It is interesting to compare and contrast our lives (mine and my uncles) as we have children the same age and live in such different worlds.
He and his wife were very concerned with school choice (ended up at a Steiner school; it is her third school as the others weren't "a good fit") whereas we have only one school, so that's it. I accept that I will have to adress gaps in my son's education myself.
Also they allow their dd to behave on ways that I find plain rude...they do not require her to answer when someone asks how she is because she is "an introvert", for example. And when I've visited them it seems that most of their circle parents this way.