Most babies grow their first tooth sometime between 6 and 12 months old, but some do start teething earlier, so it may be possible that your baby is teething at 3 months old or even 4 months old.
Check for symptoms of teething like fussiness, excessive drooling, or sore, red gums. If you aren’t sure whether your baby is teething or not, ask your child’s healthcare provider for personalized advice.