I had a son who was just like this. He continued to pull my chain throughout his childhood. I agree with the other advice about discipline and giving yourself a break that you've gotten.
Each child has a different personality that they're born with. There is always a good aspect of that personality - or it can be channelled in a good way. My son was very curious and wanted to learn through exploration, so I did everything I could to give him safe opportunities to do that. I taught him to learn to like books, which can be calming by using cardboard or plastic ones about trucks and things he enjoyed. I challenged him with games. I put him in a playroom with child-safe gates when I needed a break and he was young enough so I didn't see his behavior as "bad". Giving him "time out" didn't work until he was 3.
I know you have limited time and I can't relate to your working with young kids since I was a family child care provider (making my income at home taking care of other people's kids). But child care providers are educated in this field and since you pay for it, use them for this kind of information.
BTW, today my son is a government contractor doing amazing things.
- J.
Mother, grandmother, substitute teacher, religious educator
http://www.joycedowling.com/