Out of control nearly 3 yr old!!!

Hi Guys!
I have 3 children but my nearly 3 yr old son Jayden just can't leave his 5 mth old sister alone. Today for example he tried poking her eyes out with my car keys when i wasn't looking in the supermarket trolley! Lucky I just turned around at the right time. I put him in time out at home if he hurts her but when he comes out he tells me he'll be good and says sorry but 5 minutes later we're back to square one!!! What should i do? I'm desperate!!!!!

Hi,
I'm curious if you ask him why he was on time out. Does he know or just mumble something about nothing. Does he remember what he did? Maybe if he leaves time out and keeps on doing the same thing again and again, you should a lot the time he will need to spend in timeout. I know that diversion is a good idea also and praising Jayden for not hurting his little sister will help.