My kids started out with an older pediatrician and an older dentist. Both those docs told me there's no such thing as a normal chronology for teeth - they will come in when they will for each child (that was a real relief up front).
The most important thing is to start early keeping your baby's teeth healthy, so they're very used to brushing (whether with a baby tooth cleaning "glove" or a pediatric brush) and to make going to the dentist a very comfortable, familiar event. It's all so much easier without the freakouts.
Oh yeah, and when the dentist tells you to avoid high fructose corn syrup, believe him/her :)