Many family/general dentist start seeing children around five or six depending on the child. Some will see younger child if child is able to visit the dentist without much fuss. However a family dental office is not always set up to handle very young children and in that case seeing a pediatric dentist is best advise.
When buying dental insurance for a child one to five years of age, make sure the plan you are reviewing provides some benefits for specialist. Pediatric dentist are better equipped to handle younger children because they are specialist, where as many dental insurance plan limited the coverages they offer regarding specialist needs.
Also make sure that if you are going to buy a dental insurance plan that makes you stay within a network of providers make sure that the plan as some pediatric dentist within their plan that your child is able to go to if necessary.