I was 26 when I had my first child.
That's not too early in my opinion, in the sense that, at 26, I was already a responsible person, with a secure job. At the same time, the lower age difference means that the generation gap is not as wide and improves communication, specially if the parent keeps a young attitude.
But it was too early in another sense. I married at 23, which was waaaay too young, lost chances of doing things I now know I would have liked, and ended the relationship in a divorce.
Now that my oldest son is 23, I both enjoy the communication benefits and realize how stupidly early in life did I marry.
I was 30 when my second son was born and 39 when my daughter was born.
As I see things now, 30 is perhaps the ideal age, and 39 is not bad at all... so it's only logical that people -and specially women- wait until their thirties to be parents.
I hope my kids wait until their thirties... I don't want to be a grandfather too soon