To break this habit, you will have to get up very early one morning (when you have plenty of time), and get your puppy out on a walk before it has had its morning wee. You should not bring it home until it has been forced to go out of desperation. If however, you are unsuccessful, and your puppy has not toileted, then take it immediately into the garden on your return, or you risk it relieving itself indoors. Need more help? Follow these additional puppy training tips (e.g. socialisation techniques to prevent behavioural problems).
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. What Is Pointing In A Dog ?
I don't teach or recommend so-called "purely positive" methods that allow misbehaving pups to continue misbehaving, instead of teaching them which behaviors are and are not allowed. "Purely positive" is fine for teaching tricks and high-level competition exercises, but NOT for teaching the solid good behaviors that all family dogs need to know, and NOT for stopping behavior problems such as barking, jumping, chewing, nipping, chasing, etc. How Long Does It Take To Clicker Train A Dog ?