I agree with the others, it depends on the person. It can be REALLY hard sometimes. Are you ready to have an extra appendage attached to you everywhere you go? I mean of course it is the most beautiful and wonderful appendage in the world... but you know what I mean. If you want to take on a LOT of hard work now when you could instead be footloose and fancy-free for a few more years then that's your choice. I'm speaking from the total opposite end of the spectrum here - I put it off for as long as I possibly could. BUT, I wish I had them perhaps ten years earlier, since for example, when my twin boys are my age I will be approaching my final years, which is really quite sad.
women can safely birth into their 40's. And the life expectancy for women gets higher every year. All I am saying is there is no rush. And yes, you do get to experience different things when you are single vs. a mom. I think motherhood is great! Can't wait to have a baby myself, but I spent over a year backpacking and traveling all over the U.S. and Canada. Just quit my job and went. It was the best time of my life. Something I would not have been able to do if I had a baby to care for. Time helps you get a better sense of who you are and what you want from life.
I can't speak for anyone but myself, but for ME, that would have been much much much too young. I wasn't ready for the responsibility of having kids until after my 30th birthday. Some women really are ready much younger than I was, though.