Between 4 and 7 months old. An early developer may get his first white cap as early as 3 months.
4 8 months most infants start teething between 4 8 months of age there is a very wide range of what is normal i have seen several infants born with bottom front teeth already and many who didn t get their first tooth till 9 14 months old in almost all cases it just works it own way out as the child grows 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 Teething usually begins around 6 months of age. But it is normal for teething to start at any time between 3 months and 12 months of age. By the time your child is about 3 years old, he or she will have all 20 primary teeth. The lower front teeth usually come in first. Upper front teeth usually come in 1 to 2 months after the lower front teeth. Here are some tips to help your baby feel better while teething: 1  Use a clean finger (or cold teething ring) to gently rub your baby's gum for about 2 minutes at a time. 2  Many babies find this soothing, although they may protest at first. 3  Provide safe objects for your baby to chew on, such as teething rings. The vast majority of babies sprout their first tooth when they're between 4 and 7 months old. An early developer may get his first white cap as early as 3 months, while a late bloomer may have to wait until he's a year old or more. Some babies get through teething with no problems at all, but many parents report that their babies do experience discomfort. The symptoms most likely to trouble a teether include: 1  Irritability or fussiness. 2  Drooling (which can lead to a facial rash). 3  Gum swelling and sensitivity. 4  Gnawing or chewing behavior. Babies' teeth start to appear from around six months. The loss of that cute, toothless grin is a big step towards being able to eat solid food later, but can bring with it some pain and upset for babies and some hard work soothing a teething baby for parents.  By age 3, your child should have a full set of 20 baby teeth, and they shouldn't start to fall out until his permanent teeth are ready to start coming in – around age 6. Some babies get through teething with no problems at all, but many parents report that their babies do experience discomfort. The symptoms most likely to trouble a teether include: 1  Irritability or fussiness. 2  Drooling (which can lead to a facial rash). 3  Gum swelling and sensitivity. 4  Gnawing or chewing behavior. However, all babies are different and the timing of teething varies. Some babies are born with their first teeth. Others start teething before they are four months old, and some after 12 months. Early teething should not cause a child any problems, unless it affects their feeding. A rough guide to the different stages of teething is: 4 9 months babies usually start drooling and putting fingers in mouth by 4 months sometimes they can show all symptoms of teething a good 2 months before you see the tooth pop through it is ok if you see no tooth even at 9 months as long as the baby is growing fine and is not completely bald 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 Most babies get their first tooth at around 6 months, but your child's chompers may appear as early as 3 months or as late as 14, depending on such factors as when Mom and Dad started sprouting teeth and whether or not your baby was a preemie (preemies tend to teethe on the late side). 
https://www.healthtap.com/topics/how-young-can-baby-start-teething http://www.webmd.com/parenting/baby/tc/teething-topic-overview http://www.babycenter.com/0_teething-your-babys-first-teeth_11243.bc http://www.webmd.boots.com/children/baby/guide/teething-symptoms http://www.babycenter.com/0_teething-your-babys-first-teeth_11243.bc http://www.nhs.uk/Conditions/pregnancy-and-baby/Pages/teething-and-tooth-care.aspx https://www.healthtap.com/topics/how-young-can-baby-start-teething http://www.parenting.com/article/guide-teething-symptoms
how young do babies start teething