Research and experience shows that an intensive early education program of at least 20 hours a week of instruction from an experienced teacher can help rewire the brain and influence behavior. The brain is still developing which makes it an optimal time to alter it's course. It's harder to influence behavior when a child is already set in their ways. Sometimes, I receive students who are 12-14 years old, who have been living at home and getting what they want, so that their behavior can be controlled. This is no fault to parents, they are just doing the best they can in their situation. But, at this age it is harder to undo these behavior patterns. 
It is important to keep children with Autism engaged academically and socially. If a child is left hours at a time stimming or playing video games, this just allows them to retreat further within themselves. Some Stim time should be allowed but limited.  
Temple Grandin recommends the book Early Intervention and Autism: Real-life Questions, Real-life Answers by Dr. James Ball
This book provides information on interventions, teaching strategies, program planning and behavior management.


Sources: The Way I See It by Temple Grandin PHD