I have a 2 year old and I waited - I am 32 now. I knew I wanted to have kids, but thought later would be better - now I somewhat regret that.
You start to think of a lot of shit after you have kids, and one that I didn't think about - and maybe not relevant to some, but is the relationship with my kid and my parents. Having waited, I now realize my son will only remember/view my parents as elderly - my son won't be able to play ball or do many active things with my parents, which is disappointing. Other issues with waiting, is while it would seem better from a fiscal and time standpoint, it really isn't. Kids take up a lot of time with schools, doctors, etc - it would be much easier if my son were say 6 or 7 now and could do a lot more things around the house, ride the bus, etc - time that I and my wife don't have to spend away from our jobs while we are still in our best business growth years. Fiscally, kids are really not that expensive - except for fucking daycare, that is a racket. Diapers can be expensive, but a lot of that you will get from baby showers and gifts and as soon as you join the babysrus clubs and stuff it gets easier. Ultimately, you want to be saving for your kids as early as possible, so since I didn't start a fund for my kid til he was actually a living thing, I am behind on saving for college or whatever else he decides to do.
Probably long winded - kids are good, don't wait too long. If you are thinking about waiting til mid/late 30s, watch Idiocracy with Luke Wilson. No offense to those who do, this is just my take - because I waited a couple of extra years after getting married than I needed to - granted on flip side is i would have missed out on a lot more quality time with my significant other, fun trips, late night partying, all the things I can't do now.