Not Cuddly Only Bitey

My pup is now 10 weeks old--mini Aussie Shepherd. I haven't once had a cuddle session with him. If he's close he's biting. He constantly has his mouth open and is chewing. He chews my fingers, hands, forearms, calves. He grabs at my pants and sleeves of my shirts. The trainer said that this will settle down at 4-5mos when he gets his adult teeth. Is this true? Right now the only little pets I get in are when he's chewing on something near me or chewing on me!