How common is it for a baby to have the majority of his teeth come in at once? It appears that my son's getting all but the standard first teeth.
Teeth usually begin to come in at 6 or 7 months, and they tend to arrive in pairs. The bottom two central ones come first, followed by the top four about two months later. Another month or two after that, the next two bottom incisors emerge.
But teething times are variable, and early or late teething is a pattern that runs in families. For some babies it is a quicker process and many can seem to come in quickly and close together. This is normal.
What I can't tell from your question is whether the sequence of which teeth are emerging is out of order in your son. By "standard first teeth" do you mean that the center ones aren't in while the lateral ones are? Top or bottom? If the order does seem different from what is outlined above, you may want to talk to a pediatric dentist. A set of X-rays can be done to see if any teeth are missing.
You can find answers to frequently asked questions at the American Academy of Pediatric Dentistry website, as well as a directory to help you locate a pediatric dentist in your area. If your son's teeth are coming in in an unusual order, I'd recommend giving these specialists a call.