they start losing their deciduous (baby) teeth at around 4 months old. They ussually start losing their incisors first (the little ones at the front - sorry if you already know that!!). By 6 months old your puppy should have his/her's full set of adult teeth. Sometimes the deciduous canines dont drop out even when the adult canine has come thru, if this happens it is important to have the deciduous canines removed as they can cause developmental probs for the adult tooth. (if you have your pup neutered, ask them to check for this and remove if necessary).
lol!!! mine started to loose at 4 months ish and last teeth came out last tuesday at 6 months!!!! he's JRT and chews everyting!!!! kept supplying him with chews! he's alot better now and chews less. And my hands can recover!!!
