If a puppy is taken away from his mother and littermates too early, he may miss out on important behavioural 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. 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 socialisation process.
Remember, wherever you get your puppy from, your first task will be to arrange an appointment with your vet for a health check, to make sure he's in good condition. Remember that buying 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.