I have a 3yo dcb who has become very challenging over the last month. He used to be my sweet, gentle boy (though he has always had a knack for taking things from people), and he's suddenly defiant, bullying, aggressive and pushes the kids buttons like crazy. He does it on purpose and laughs which is really what gets my goat. Like he'll just sit behind someone and poke their back over and over again laughing while the other child is telling them to stop. He prevents kids from playing with toys (he'll block the way with a smug gri on his face), or blocks them from going int the bathroom, etc. He takes toys away from kids, and while he does listen when I ask him to do something there is always a push back excuse first (but I'm not finished yet, but I don't want to). During structured activity (crafts, circle time, games) he is cooperative and easy to love. Yesterday he hurt my son pretty badly. Without provocation, he pushed him from behind and he flew into the corner of the wall and ended up with a huge goose egg....then laughed even after I put him in time out. I let his Mom know and she was so embarrassed and offered to come pick him up. I declined, as I just wanted to let her know about his behaviour. She was so sorry and said they were having issues with him at home as well, and at playdates with bullying. I have been dealing with his behaviour with a firm voice, angry face and time outs (for the more serious offences) followed by a calm discussion on why he is in time out and why the behaviour is not ok. He listens and appears remorseful (I know he isn't), and apologizes to his victim and then 15 min later he's knocking down someone's blocks or stealing someone's toy and running away laughing. It's getting out of hand and honestly the days he is here are SO much harder then the other days. His sister just started and is soooooo sweet. Just like he was at that age.
I don't intend on terminating. I want to work on modifying his behaviour, and working with his parents to correct this. Do any of you have some behaviour guidance advice for this kind of behaviour? Because what I'm doing isn't working.