3 yr old bossiness

My youngest son is 3 years old and was diagnosised as being developmentally delayed and having ADHD when he was 2 years old.  One of the problems we are having with him now is that he is extremely bossy.  

For example, he will scream and yell at anyone who tells him no or trys to displine him or he will bite.  Sometimes he has even pushed and done the exact opposite of what he was told to do.  When we have put him in time-out it seem not to help his behavior at all, just made it worse.  Now, when we tell him that he is gonaa to go to time-out if he doesn't stop what he is doing he will put his hand on his hip and say "I'm gonna put you in a time-out cuz I ain't gonna you are."

I just have no idea how to respond to him.  I normally have just told him that that behavior was unacceptable and put him in time-out but I am wondering if there is something else I should be doing.  When he is in time-out he gets up and gets toys to play with and just doen't seem to understnad the time-out.  

When he is at preschool they have no issue with him an dhis behavior except  for only once and he sat in time-out for 5 minutes and never whimpered,cried or got up.  Why is bossy at home and not at school?

Thanks in advance.

[Kevin Kennedy, Ph.D.]

Your son apparently behaves well in his pre-school seting, indicating that the problem rests in the parent-child interaction. Your description of your limit-setting and discipline conveys the sense that your method of implementing (and following through with) time out is flawed. Use the SEARCH function in this Forum, and you will see many replies about Discipline, Time Out, etc. Also, read S.O.S.: Help for Parents - this will offer you a practical road map through the technique, along with other ideas about discipline.