H.K.
I have never found time-outs to be effective (except ironically for my teenager who does get sent to his room to cool off if a disagreement gets heated).
Anyway, I always used the concept of "swift and terrible". This only works well if your basic personality is loving, funny and humorous because it requires a sharp contrast.
When one of my small children would misbehave toward another I would swoop in, get directly in their little face, hold the offending hand that had hit firmly and with my most serious and lower toned voice would say "Wrong!" (I didn't use "No" becaause that has a tendancy to get used to much).
The change in my tone, behavior and expression was generally pretty shocking to them. They didn't like to displease Mommy after that because they liked the "nice" me. By using just that one word "wrong", I was able to communicate to their little brains that what they were doing was just that..."wrong".
Anyway, hope that gives you another idea.
P.S. Keep in mind that not all of the hitting, pinching, biting is wrong. Boys need to develop that to some extent, it is all part of their make up to jostle for rank and challenge each other. I turned a blind eye to most rough housing with my guys unless it looked like it was a victim /aggresser situation. When the rough housing was returned in like, I allowed it and still do.