This is such a common question that we get at Sublime K9 dog training company. People may get a puppy as early as 8 or 9 weeks old and are looking for guidance.
We believe that you should begin training your puppy the minute you take them home.
At Sublime K9 dog training, we use marker training with our puppies. Marker training is a force free, all positive, method of training that can be used at any age. If you start at a young age you will lay the groundwork needed to have a well behaved, well mannered dog. There really is no reason to wait and it will help avoid problems from developing in the future. It will build a strong, trusting bond between you and your dog.