Puppies can begin very simple training starting as soon as they come home, usually around 8 weeks old. Always keep training sessions brief — just 5 to 10 minutes —and always end on a positive note. If your puppy is having trouble learning a new behavior, end the session by reviewing something he already knows and give him plenty of praise and a big reward for his success. If your puppy gets bored or frustrated, it will ultimately be counterproductive to learning.
Keep your training sessions short, consistent and always have fun. The key to shaping your puppy's behavior is to start out with very easy commands, continue to build on these successes and apply heaps of repetition. Base your puppy training sessions around trust and mutual respect rather than old school methods based on punishment, avoidance and harsh corrections. In this environment you will find that your puppy loves his training sessions and his confidence will grow with each and every session.
It typically takes 4-6 months for a puppy to be fully house trained, but some puppies may take up to a year. Size can be a predictor. For instance, smaller breeds have smaller bladders and higher metabolisms and require more frequent trips outside. Your puppy's previous living conditions are another predictor. You may find that you need to help your puppy break old habits in order to establish more desirable ones.