In a way it will vary. but on average teething can range from 6/8 weeks - 6/8 months. (This is an estimate to the fullest extent.) The chewing could still continue, all depending on the breed.
check out the link for good info on teething puppies and how to deal with the associated chewing things.
How long does it take for a puppy to start losing baby teeth?
my dog was a couple of months old when we started finding teeth i think...
Reply:My lab started getting his "grown up" teeth around 4 months old. His cainine teeth came out around 5 months and bled like crazy which the vet told me was normal. He is now 19 months and still has a couple smaller teeth, which we were told was also normal.
Reply:They can start losing teeth anywhere from 3 1/2 months-4 1/2 months old.