FWIW,
In answer to your question, yes, ADD/ADHD can present in the early school years. In fact many in the field say that you really can't accurately assess ADD/ADHD until the early school years. However, while a child can certainly be both gifted and ADD/ADHD, it is a label to be very wary about.
I have been searching for about 3 years to find a Psychiatrist that can truly answer that question for our son. So far what we get is that he looks like he is ADD/ADHD combined type. However, we do not medicate and his behaviors are slowly improving. If your daughter has been in an academic setting that has not challenged her, she has also probably picked up some bad coping techniques. It will take time for her to learn to tune into the class instead of daydream
I think you are right to work with her on paying attention and providing other outlets for her wonderful imagination.
