You could, but its not ideal in my opinion.
A dragon under 16 inches still has quite a bit of growing to do, which means that dragon still needs to be taking in large quantities of protein. The amount of fat in superworms compared to their protein content makes them not ideal for meeting the protein requirements of smaller dragons.
Smaller superworms are fine as a treat for smaller dragons, but I wouldn't rely on them at all as a staple feeder until the dragon is an adult.
Just to clarify, the reason supers aren't recommend until a dragon is 16 inches in length, is because until a dragon is 16 inches, it has a kink in its digestive track that makes it tough for the supers to pass through. Once a dragon gets big enough, this kink straightens out.
-Brandon