We do not start potty training any of our pups before 8 weeks of age. Until about 4-5 weeks the pups get there food from their mother's milk and there is very little undigested waste, the mother cleans up most of what waste there is.  Once the pups are able to climb out of their whelping box they generally will leave the box and go to one area of the whelping kennel to eat and another spot to excrete.  They learn this by following the example of their mother.  We begin feeding solid foods outside the whelping box around 4 - 5 weeks of age.  The puppies will generally leave the box to eat and drink then go to the duty area to relieve themselves shortly after they eat.   Usually when given the option they will not normally soil their sleeping area.  If forced to soil their sleeping area by not being let out they will become accustomed to doing so and are harder to break of this practice.  When starting potty training we start with crate training, we usually put a small sleeping kennel inside of a larger crate or box.  We cover the floor of the large box with news papers and put a small piece of blanket material in the sleeping area.  They will then if not taken out enough usually pick a spot in the larger crate area as a potty spot and you can change the paper when you get back.  Gradually you can reduce the area covered in paper and they will usually adjust to using the paper potty spot area.  At eight weeks a puppy will only be able to hold their bladder for about 2 hours so we take them to the area we want them to use for potty duty about every 2 hours.  Gradually we increase the time between potty breaks so by about 14 - 16 weeks or so they are able to hold their bladder for longer periods of time.  While training we recommend giving them their food and water 2 - 3 times daily during the hours that someone is available to take them out and always take them out right after they eat and drink.  Others use different methods but this method has always worked well for us.