I had DD at 30, and even now I think there are things I should have done before having a baby. I lived overseas, travelled extensively, got a degree, built a career, bought property, got married, lived the high life for a while... But I regret not changing my career path. It'll be much harder now with DD and I'll have to take a lot longer to get there.
So I guess age isn't really the issue, it's just about being as sure as you can be that you're ready for the challenge. If you're putting anything off, do it before babies.
Also, I had a really tough time with DD for the first few months - she was sick and screaming all the time and I developed PND. The reality of having a baby is so different to the idea of it, and it can really put pressure on your relationship. If you both have the emotional maturity to handle it I'm sure you'll be fine, but make sure you're 100% honest with yourself when making the decision.