Both of my children went in around age 2-1/2 for a meet with the dentist and count how many teeth they had, from that point on every six months faithfully I take them for check ups and cleanings.
Funny that you mention that, I spoke to the dental hygienist in my dd's school the other day, she came home with a form to fill out by the dentist ( which coincidentally we had seen the day before ) and when I called she said to me that she wishes all the parents would do that but not too many parents in that school do that. My kids already have their appointment for the first week of August done and this week I'm calling to schedule an appointment for their physical probably before they finish school, yes I do it then because in the summer the doctor's office gets crazy with that.