Although it can be very exciting when you first bring your puppy home you need to address any biting immediately.
Failure to stop your puppy from biting can lead to problems with aggression and biting when they are an adult.
In the litter your puppy would get a sharp bite from one of its litter mates if they bit them so they would quickly learn not to do it! You should try to avoid bringing your puppy home before they are 8 weeks of age to ensure that they get the maximum amount of time to learn not to bite from their litter mates.
When trying to get your puppy to stop biting it is recommended that you do not smack them.
Smacking can be mistaken for playing or your puppy might become scared of you which may lead to aggression problems when they are an adult.
Also playing games that involve wrestling with your puppy can lead to nipping, even if at the time you thought you were just playing.
Giving your puppy something to chew can be a way to redirect their biting along with a firm 'no' when they bite your finger, to teach them the toy is OK but not your finger! If you want to try to replicate the situation in the litter you can mimic the sound of a dog yelping every time they bite, you instead of saying 'no'.
You want to startle your puppy with the noise so that they leave you alone.
If you have started to train your puppy and they are still biting you then you should consider attending obedience classes to get a professional's help to stop the biting.
Your relationship with your dog will be more enjoyable if you can stop your puppy biting from a young age and you will be less likely to be faced with aggression issues when they are an adult.