Behaviour modification techniques?

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.

He gets time out or sent to a designated play space for every offence no matter how minor because it is bullying. While you may not be able to get through to him that that is not how we treat our friends at least you will be protecting the other children. He needs to be given rules that include keeping a one foot radius from anyone else or what they are doing and must stop, ask if he may play too and then play. At first sign of not playing nice he goes back to his pillow or whatever.

As far as home goes there should be no play dates with anyone he has bullied to teach him that no one wants to be his friend if he is going to act that way and that it is a privilege.

This is another situation where I feel making him go over to the child later and apologize is in itself perpetuating the bullying because he likes the attention it gets. Reminding the little kid that hey I am bigger than you and I hurt you and ok fine I'll say sorry it just has the big kid standing in the little kids personal space pretending to be sorry but really rebullying the little kid with your permission. Just my opinion. Not a fan of making a child say sorry. I praise if they do it on their own but do not make them do it.

For some children, time out's just do not work. If you feel that this is the case then I would try implementing a different consequence for his behaviour. I have a 3.5 yr old dcg who was like this. She didn't care if she was in time out or if she was in time out for a long time. She would take her time out and within minutes be back in one. I have pink and green chairs and the pink is her favourite so now her consequence is if she doesn't behave all day she doesn't get to sit on the pink chair at afternoon snack. This has worked MUCH better and she is now in timeout 1-2x a week instead of 4-5x a day!! I will also not allow her to play with her favourite toy if it is really bad behaviour. Some children need a more visual and concrete consequence than just being on time out.

She is also very spoiled at home and I would tell her parents every day about her behaviour and why I needed it to stop especially after the younger ones were copying it. Dad was on board but it took mom awhile and they now give her more consequences at home as well. Her parents are very intelligent and know what to do but they aren't the greatest at following through. Mom admitted she spoils her children and finds it hard not to do. I think by me telling her over and over every day about the negative behaviour she finally realized that she wasn't helping her daughter by not giving consequences. She is still a handful and mom still has a long way to go IMO but it is much, much better!!

This won't help in this situation but for others do not be afraid to crack down on the kids when they are very very little for doing behaviours that seem bent on annoying others as it escalates when they get older and can become a major issue such as described here. Too often we let things go because they are little without realizing that what that 18 month old is not his way of trying to play with the other kids but is him being wilful and destructive on purpose. The sooner rules are put in place to limit the behaviours the more likely it will be over before the child gets older or at least you will have a system in place. One of the reasons we have more problems with children we get later in life than when we start them as babies.

Bullying is very much in the news these days and some studies will show that when they go back in a child's history that there were signs when they were much younger that they did not have empathy - the ability to understand how others felt or self-control - as in was too impulsive acting first and thinking later. Two skills we need to work on with toddlers so they are innate abilities as they get older.

I've been having the same issues with a 2 year old boy, he's been here for a year. It has been a constant issue. Mom seems to be on board and claims to be disciplining each time. I've started giving out stickers when I witness a kind act by one of the children. I've also been separating this child from the other children whenever he demonstrates bullying behaviours. Hopefully these two ideas will work.

I have a little boy that for some reason likes to hum. (I think its a comfort thing) Well it gets on my nerves, because its the same pitch and it goes on forever..Kinda like a buzzing light or a dripping tap....

He has a humming chair; every time it starts that's where he goes without fail.....And the humming is getting to be less of an issue. Because he feels like he is missing out when he sits alone in the kitchen in his chair. Too, he also knows that he can go to his chair when he feels that need.

Note: I do not punish him in any way, this is just a way for him to hum without drawing attention...It was actually making a dcg cry.