I just took my 2 1/2 yr old daughter to the dentist on Wednesday. It was just for a check-up because her father's parents and siblings all have awful teeth. I'd rather play it safe! Everything went well.. she fussed a little when the dentist looked in her mouth but then they gave her a toy and a toothbrush. You would have thought it was Christmas! She's still talking about it.
I was told that it is normal to wait until children are over 3 years old unless there is a specific issue. The dentist said it's really up to the parent though, and of course what the child will tolerate. He said as long as the teeth are brushed well and often (and you stay away from giving them anything other than water to drink after bed)there should be no problem.
Also, he said that the majority of dental traits passed down to children are passed from the mother's side which I thought was an interesting factoid.