No puppy should leave it's mother and litter mates until at least 8 weeks. For smaller breeds, such as the Yorkshire Terrier, 10-12 weeks is preferred. No good breeder would ever let a puppy go before 8 weeks of age.An 8-12 week old puppy isn't old, so you'll still be getting a young puppy.eport Abuse. No puppy should leave it's mother and litter mates until at least 8 weeks. For smaller breeds, such as the Yorkshire Terrier, 10-12 weeks is preferred. No good breeder would ever let a puppy go before 8 weeks of age. An 8-12 week old puppy isn't old, so you'll still be getting a young puppy.