The question when to start dog biting training is quite controversial. Some dog owners consider that dog training biting should be started not earlier than when a dog is 1 y.o. But many dog owners prefer to start puppy biting training earlier.
Both of them are right. The development of dog aggression should be started only after dog's age of 12-16 months. But the earlier you start dog bite grip the better. There are special exercises for this work when a puppy is trained in a playful manner to a future guard work. One of these means is exercise with a dog bite tug.
Dog bite tug is a pad made of dense fabric and stuffed with synthetic filler. They may have 1 or 2 handles. Our dog bite tugs by ForDogTrainers are made of leather, jute, French linen, or fire hose.
Dog bite work may be started since your puppy is 3-4 months old. The first skill to train is to make your puppy chase you and catch a bite tug by its teeth. 
Hold it horizontally at the level of puppy jaws and wave it from one side to another. Give it away at once when a puppy grips it.
Never pull a tug strongly from dog's teeth. If a dog gets unpleasant feelings towards this work and item in early age it may intervene further bite grip training.
Exercise should not take much time. Repeat it 3-4 times while walking. Each time there is one chase, one catch and give away of the tug to a puppy. Never make a dog tired.
While training of dog bite grip depending on the stage and success start to resist your dog, play "tug of war". Let your puppy win each time and get the "prize". When a dog actively chases, pulls and grips a tug tightly in its teeth, you may start to train it release a tug by a command "give". Make it after some time when a dog runs around with a tug in teeth.
Approximately at this time start to use a handle. For this when you give a tug to a puppy, do not release a handle but pull it a little playing with your pet.
While this work start to train a dog to sharp and clear swings. If each swing is followed by petting your dog will quickly get used to it. It will help when a dog will work with a helper, at about 1 y.o. When he will start training a dog to beats it will not cause problems, as a dog will be trained to such threats.
Consistency is an important rule in training. Go slightly from petting to a sharp swing throughout at least a month of exercises.
When a dog has a stable interest to chase a tug, you may use it for training of basic dog obedience skills. To train a dog to move straight by your command keep a tug in front of you, at the level of your belly. Give a tug only after sit of a dog in front of you. To train "heel" move keep a tug at the left side. Praise a dog by giving the tug after walking along some distance by your side.
Stability is an important condition in tug training, as in any other one. If you will spend 5-10 min daily for dog training with a tug, you will get the result quickly.
