I agree with DeeDee that most professionals won't (probably rightly) make an ADD/ADHD diagnosis as young as 4 years old. And with Mamabear that you should also check out other possible conditions.
If your son has issues interfering with daily life and learning, there are lots of interventions you can try even without an official diagnosis. I think Grinity mentioned most of them:
occupational therapy, sensory integration therapy, structure and good sensory diet at home, parenting strategies (like Nurtured Heart and my new favorite "collaborative problem solving").
