The general rule with regard to the age to start training is six months. However, depending on the particular breed and temperament, this rule should not be inflexible.
Some large breeds that are fairly often of very dominant nature – for example the Rottweiler and the Pyrenees – are going to grow into very strong powerful animals – and training should begin quite a bit earlier, usually four months.
General socializing with other animals can start as early as three months, after the pup has had it's shots.
Obviously it does depend on your previous experience with dogs. If you have had previous experience with dogs and happen to be a dominant sort of person there is no need to start very early. You will have established a sense of control and obedience with your dog quite early and the dog will know by the firmness of your handling that you are the "leader of the pack".
If however, you have not had a great deal of experience in training dogs, it is definitely advisable to start early, specifically with socializing the pup.
Remember though, that it is very young pup that you are training. Do not be too harsh in your training methods. Allow the pup to enjoy the process. Do not forget to indulge in a great deal of play when you are not involved in the formal training sessions.
Most pups have a certain amount of prey drive – some more than others – but this should be encouraged from a very early age.
Start with a soft slipper in your passage, so that the pup hs to return to you, and not run away.
Get very excited in the process of throwing the slipper and praise very enthusiastically when the pup returns holding the slipper.
Dog's vary a great deal in temperament even within a certain breed. With German Shepherds for example, this is particularly noticeable. I've had German Shepherd pups that are so awesome to please they are an absolute joy and delight to train. A few, but unfortunately very few, have been so obstinate and self-willed it has been a battle not to be too dominant and spoil their spirit.
You have to make an intelligent assessment of the temperament of your own particular dog – regardless of the breed – and adjust your training to suit the dog.
Border collies, for example are remarkably intelligent and generally speaking very easy to train. However, they often need firm, but gentle, handling to establish your authority.
Note: This information is relevant for those who want a well-behaved dog, and for those who intend the usual obedience tests. If however, you are interested in the sport of Schutzhund, there are many expert trainers who suggest that it is not advisable to start any training at all until the dog is far more mature at approximately 14 months, and even later.
There is some merit in this point of view, because in Schutzhund training the accent is often of "drive". Early training can sometimes make a dog obedient but not quite as enthusiastic as it is required to win at the highest level.
Obviously a great deal depends on the breed of dog you are training; the dog's temperament and of course your own temperament.
You'll find a great deal of useful information about obedience training on the following website: www.freedogadvice.com