At what age do puppies get their back teeth?

My baby that I rescued does not have back teeth yet and I am trying to determine her approximate age. We guessed 6 weeks. She barely has started to chew on anything and I have to feed her canned puppy food for now.

between 2 and 4

Around 4 months of age your puppy will lose its first set of teeth and the adult teeth will begin to emerge from the gums. The teething process continues on and off for several months and, as with human babies, this is often a painful or uncomfortable process for your pet. You will be able to work out when your pet is teething from his increased chewing and biting on everything imaginable that is within reach.Check her teeth every so often. You will be able to see and feel loose teeth and may be able to find some. Young puppies chew because that's how they learn their surroundings, it is more than natural.

I think it is 2 and a half

I had this conversation with my vet yesterday regarding my pup. It's hard to tell exact age until they start loosing teeth. The first pair of front teeth are lost right around 3.5 months, the next pair at 4.5, the next pair at 5.5, and the last pair at 6 months.