The little nub tail is not the norm. The official Yorkshire Terrier Standard in the US states the tail should be docked to a medium length.
Yorkshire Terrier Page
Of course there are many people in the US and other countries breeding only pet quality dogs and they know little about how the tail should be docked. Even many vets just guess at what they are doing. It is actually dangerous to dock so close to the spine as it can cause permanent damage. Some poor little ones can hardly wiggle their tails back and forth due to improper docking.
The tail will grow as your pup grows but it will not increase in length.