I think most babies wait until at least 6 months to begin teething, but it seems as though they discover how much fun it is to shove things in their mouths at around three months. I have about 2 months worth of fotos of my firstborn with her fist stuck in her mouth in every one of them. My kids got their teeth late-at 10 months, but my friend's baby got her first two teeth at 4 months. It really varies. You might ask when you got your teeth. I think they have to go through a period of excessive drooling and crankiness before the teeth actually break the surface,though. It seems like we always figured it out after the fact. "oh she's been cranky for the last week. Oh look, there's new teeth, I guesss that was why!"

around 2 months or so babies begin producing much more saliva, they don't know how to swallow when they're not eating so out it pours. a lot of people take this as a sign that the baby is teething.

she could be teething, but 3 months is pretty early. there are a few babies on here that got their teeth that early though, so it's not impossible.

i think 6 months is the "average" though.