If a puppy is taken away from his mother and litter too early, he may miss out on important behavioral and emotional development stages. Ideally, a puppy can be adopted between seven and nine weeks of age.
At first, you will have to keep your puppy sheltered in your home and yard. Check with your veterinarian to make sure your puppy has been vaccinated adequately before introducing him to other dogs. Usually at around 13 weeks old, about a week after his second vaccination, you may start to gently introduce your puppy to other people and dogs, thereby starting the socialization process. Earlier socialization may be done with screened people and pets to minimize risk of disease spread.
Remember, wherever you get your puppy, your first task will be to arrange an appointment with your vet for a health check, to make sure he's in good condition and to ask for a puppy food recommendation. Remember that a puppy is more than a financial investment; it's an emotional one, too. A little research and some careful thinking now will pay off for the both of you in the future.