These foundation skills can be started on puppies as young as eight weeks old.-fyi If it was me get yourself a burlap sack. Burlap has nearly the same texture as bite sleeves used in training. Wave the sack close to your dog and encourage him to bite it. High praise when he does. Let go of the sack as soon as your dog bites on it. Allow him to “win” and take control of the sack. Biting the sack is the action you want from the dog, to take and allowing him to win and to control the sack helps build confidence and encourages a firm, full-mouthed bite from your green dog. Continue playing with him and the burlap sack until he willingly bites on it with a full, hard grip. Remember to Always allow him to take control of the sack and win the game, so that he is continually encouraged to keep biting. With you toy I would like to see it first, before giving advice. But the best one I can give you is to take him to a trainer and allow them to teach the proper bite. The way Bernie is biting common for a green dog, some are born with the know how, but most need to be taught. Best thing I can mention is holding it still and not moving until your dog has taken hold with the bite you are looking for. Hope this helps!