The correct time to take a pup out of the litter is at 7 weeks of age. You will hear this over and over again in working dog circles. The reasoning is that up to that age the pup gets imprinted by the other pups and the mother learning important social skills necessary for living with other dogs and to an extent people. If left any longer it will start to form a stronger bond with dogs and will not bond to people properly. Also socialization to other stimuli must begin then or the dog may never fully accept it. Taking a dog out of the litter too early is supposed to correspond to problems with other dogs into maturity. I've never had experience with this. Taking a pup out too late corresponds to a dog that doesn't bond as well as it could have with his people, and prefers following dogs. Also avoidance problems with strange/new stimuli. This I have experience with as it is the more common scenario. Of course sometimes it can go well either way or go bad even if taken out of the litter at the correct time. Sometimes people for one reason or another do not have a choice of when they can take a pup. For me starting on the right foot means taking a pup at 7 weeks. This also allows me to test the pups in the context of the litter as they usually will all still be there. At 7 weeks pups will show you temperament traits that may not have been there a week before. 7 weeks is the latest time to do tests with the pups as a litter before you're starting to run into socialization problems, consequently it is the best time.