Advice on Having a Baby

My wife and i are both 27 years old. She is a graduate from college and working. I'm getting a master's degree, and will not be done for another two and a half years. If we wait until 33 or 34 to start having kids, we cound have some trouble conceiving. And if it takes us too long, she could give birth to a mentally challenged child. So what do you think, bill? Any advice? Ah, that's some pretty heavy shit there.