My youngest was born with a tooth. My oldest started teething at 4 months. Normally children start between 4-6 months. Every child is different.
Lol... it shocked it me too! He was fussy but I don't think from the tooth. When babies are born with a tooth or teeth its pretty much like a fake tooth. it doesn't stay and its not a baby tooth some people call it "Infant womb teething" which sounds scary to me lol , There was 3 sets of teeth in his gums, the tooth he was born with, then his baby teeth hiding under and then his adult. It fell out a couple months later and now a baby tooth has replaced it. I didn't find out until he was a couple weeks old that he even had it. Its kind of a neat story to tell people because not a lot of parents experience this.