I work at a Domestic Violence Shelter and I see a lot of kids that Display Violent Behavior. In those situations I usually have Mom seek counseling for the kids. I also ask them to go to parenting classes so they can learn the proper way to deal with these situations.
But I also give this advice as a Mom myself.
No one thing ever works with one child. Whatever advice you are given you KNOW YOUR child. Even though time outs may work with MOM A they might not work with your child. You have to one find the action that works with your child. And the most important thing is to be consistant. I think you should do some sit down and play time with your son and see what you can get out of him. Unless you know the perfect doctor to diagnois your child I would also be wary of them as well. I have seen too man times Doctors give out a diagnosis without even seeing the child. Make sure the Doctor is going to physically see your child. Make sure he is going to spend some time (and that means more than 10 mins) reviewing your childs case. You don't want your child labeled if it is not true. You also want to get this taken care of before he enters school.
If he is going to public school you don't want them to send him to special education just because the teacher can't "handle him". Also know that if you think your child does need an assesment the school board is REQUIRED to provide one free to you. This must be done within a certain time limit. If you have ips it takes a little longer. If you live in a township it will happen fairly quick. Call the school in your disctrict they will tell you how. You may get transferred a few times but be persistant it is worth it. I took my child to one and I learned several things that my child should have known, but I hadn't taught her.
I had a friend whos son did this same thing in day care and she took him out becuase she didnt think they could handle him. She got him to a therapist and an appointment at Riley. The diagnosed him with Oppositional Defiant Disorder. He is now medicated. His teachers say he is the best. His mom thinks it is the structure provided in the school with all the activities. He still has his moments when he is bad though.
I have worked with a couple of moms with kids that are "out of control" and I have discovered that structure has helped them. No matter what the diagnosis fragile-x, adhd, odd, sturture from mom has helped. Don't let the kids see that they have you beat either. They can sense that and use it against you.
Well Ive talked enough. I hope it helps.