Yes. No matter how adorable it may seem now, if he starts mouthing, biting, and licking toes and feet, nip it in the bud immediately. I'm dealing with this with my boyfriend and his now 7-month old dachshund. (If I have to hear, "He's only a puppy" one more time, I will scream.)
Which one is doing the biting? How you would train depends on the answer.
Maybe you should consider a new boyfriend! ;^)