Well, I had my first child 3 weeks before I turned 29, which was 30 years ago today! Temporarily feeling old.
I thought 29 was about average to have a kid; I mean I had a house, a good job, and a master's degree along with a husband. All of my mom friends in Az were my age, except one. Then when I moved here, I was usually the youngest mom. Everyone here waits until at least 35 or 40.
Personally, I am glad I am free now. My friend from college, who is a year younger than me is a 2 time grandmother and her kids are the same age as mine.