What is a good age to have a baby ?

I've been having baby fever really bad lately and I just wanted to know everyone else's opinion about when is it a good age to have a baby . I'm 20 and will be 21 in June my boyfriend is 21 and will be 22 in September and will have been together for 4 years in August . we have lived together for 2 almost 3 years now we both have great jobs I've graduate college and he still has 2 years left in college . we've talked about having a baby but never decided when would be a reasonable time to have one so I just wanted to we what you guys think .