if he is a danger to himself or others, or is simply overtly violent or angry, then medical intervention is necessary, at least in a therapy sense, and perhaps in a medication sense or a sending him away for a while sense. religious help could also be beneficial if you are into that. don't ignore it for it will only get worse. it may go away for a while, but it will come back.
It is a good idea to use short, immediate timeouts. And to repeat them a lot. Experts say that it will take up to 3 weeks to change behavior. However, as Annie said - if you use it for everything--- you will drive both of yourselves nuts. It won't work. When he does not do something the first time, then ask him if he heard mommy. Then tell him he has a choice - he can do a timeout or do what mommy asked. And cut him some slack if he is engrossed in an activity. In fact, I would make eye contact when you ask him.
The most important thing to remember is that to change behavior, the reinforcement has to be immediate, short, and consistent. Rewards and things are always cool, but kids of his age don't deal with the future very well. So I have never been a big fan of charts with rewards. But kids do love to put stars on things and can kind of have fun with charts. But I am not sure what that is teaching.
And you might want to check out the book, Love and Logic Magic for Early Childhood: Practical Parenting from Birth to Six Years by Jim Fay.
Hope this helps.
Ok, this is a long post which this forum has been having problems handling. Thus it will come in two or three parts.
Annie has a lot of good points. And she is right on about how 4 year olds behave. Some things that you can do.
First, any behavioral modification that you wish to attempt has to be immediate. To punish him for what he is doing or not doing at school absolutely will not work! You can practice things with him at home that he might carry over to preschool. For example there are books aimed at the 4 to 7 year old crowd that are meant to be read aloud to them and then practiced. You might try "Hands are not for hitting" found here - http://www.amazon.com/Hands-Hitting-Ages-Best-Behavior/dp/1575420775 and further down the page you will see "know and follow rules" and many other good books.
But, I do want to stress again - to punish him for something that he did hours earlier will not work and probably will make things worse as he won't understand. My other thought on the preschool is that my own children went through a Montessori school. It was a wonderful school. But it gives the kids a lot of freedom. A child that needs more structure will bounce off the rules for awhile. The school could turn out to be very good or very bad for him depending on how the staff works with him. I would highly suggest that you visit the school and watch how they handle incidents with other kids.
You have a 4-year-old who makes his bed? Wow.
Seriously, it sounds like you have been doing a lot of timeouts and other punishments. I don't think a 4-year-old is capable of doing something the first time you ask, every single time. He is not in boot camp, after all. You're on a better track when you talk about positive reinforcement. At 4, almost the only thing a child will react to is positive reinforcement and gentle redirection. It takes a lot of vigilance on the part of the parent, who has to head him off at the pass and distract him, but it is a whale of a lot better than having him feel he is always in trouble because Mommy is intent on never going back on her word. You're herding cats, Mommy. They have a bazillion ideas and will go all over if you don't keep them interested and focused, plus distract them so they don't jump off the mesa. It sounds to me like he is possibly mis-categorized, to have him in Montessori where there are so many behavioral expectations. In a way, it's just (a more gentle form of) control, and especially for boys this can be very frustrating. I would find a more standard preschool, where he can be a little bit more physical and less cerebral, and let him act a little more like a standard garden-variety boy.