When you teach a puppy the “Come” command, it is best to kneel down so that you are at their same level. At 2 month old puppy can only hold their bathroom needs for 2 hours, a 3 month old for 3 hours, and so on…Until they are 8 months old. The muscles in their bladder are not fully developed and they need time to slowly make it stronger. This is an important element to remember when training. Puppies will need to have a bowel movement 15 to 20 minutes after eating.
When you want to teach your puppy to catch a ball, it is often more successful if you first use a soft fabric ball since it will be easier for them to mouth. A puppy can begin learning commands from the very first day that you bring them home – 8 weeks old is old enough to start to learn basic commands such as “Sit” and “Come”. Source: Facts about dogs