I would say firmly "Ouch" or "No!" and walk away as soon as he jumps and nips. He will soon realize that this behavior ends the fun. You also need to say "yes!" and "Good Boy!" for playing nice. This will let him know which behaviour is getting him good stuff (fun keeps going, praise, attention, maybe even treats).

When you come home and greet him happily, make sure you do not over-excite him. As hard as it may be (they are so cute with their happy wriggly body, aren't they? ) you could at first completely ignore him and once he has calmed down, then reward him with attention and play.

In our house we don't touch our dogs with negative intentions, as we don't want them to fear being handled, especially touching the face. You don't want your pup to shy away from your touch, and it seems like this is what he has learned by you grabbing his nose and saying "no". For us it is just as effective to teach our dogs what is unwanted behaviour by us walking away from them!

We also taught our puppy to bring a toy to fulfill the need of "bitey-bitey", by sticking a stuffy in front of his face as soon as he started nipping. Now, every morning he greets us by carrying a toy, it is absolutely adorable! He has learned we prefer him biting into his stuffy rather than biting us, and that oftentimes the greeting ends up with a little game of fetch.

 

Oh, I love the idea of sticking a toy in his face when he nips. Our breeder and the trainer she recommended told us to pinch his snout when he bites, but if he nips and runs, we never could catch him to do this anyway.

I will try the stuffed toy route tonight!

 

Grab his snout and hold until he starts to whine. Then let go. The nipping will stop very quickly.