It's normal and even cute when your puppy nibbles and even lunges at your hand. Since your puppy has been exposed to only other puppies in the litter who naturally play with mouthing and biting, it would make perfect sense why he would assume that playing with you wouldn't be different. But as they grow and their bodies become stronger, what was once cute nibbling eventually turns into uncomfortable or even dangerous rough playing bites.
As part of your puppy’s training, then, you should do everything you can to ensure that your puppy can’t get into trouble in the first place. That way you can avoid giving your puppy lots of ‘negative’ attention which might inadvertently encourage his bad behaviour. For example, if you use a crate, or confine your puppy to one room of the house, he is far less likely to get into trouble chewing something he shouldn’t, or peeing somewhere he shouldn’t. When Should A Dog Start Obedience Training ?
Clicker training, a common form of positive reinforcement, is a simple and effective dog training method. Although it is still fine to train your dog without clicker training, many people find it helpful. With clicker training, you can easily and effectively teach your dog all kinds of basic and advanced commands and tricks. It's fast and easy to learn how to clicker train your dog How Does The Dog Whisperer Potty Train Puppies ?