Very Variable. While most infants start between 4-8 months old, it is perfectly normal to start younger or later. While rare, some children do not start teething until 12 months of age. Children who get their baby teeth late will often get their permanent teeth later as well. If you have concerns bring them to a pediatric dentist. No child is to young for a dental exam.
Usually 6 months. Teething usually occurs between 6 and 30 months. This time frame is not hard and fast as some babies start earlier and some later.
Dr Copolla's correct. See pediatric dental specialist at eruption of 1st tooth but no later than 1st b'day, for all the same reasons you see a pediatric medical specialist. Enjoy your baby.
Six month. The four front teeth; two upper and two lower; usually erupt first, beginning as early as six months after birth. Most kids have a full set (20 teeth) of primary teeth by the time they are 3 years old.