A.P.
I'll be honest...
I skipped the time-outs for a good old fashioned spanking.
I'm not proud of it, but after a few repeats he QUICKLY learned not to hit the baby at all.
I'm not a big spanker, trust me. But when it comes to the newborns safety (or his own, like running into the street), I wasn't going to play around.
Take heart--It will get better... but it may get a little worse first (my kid's acting up seemed to peak around 9 weeks when he realized the baby wasn't leaving. before that he actually kinda liked having the kid around).