Time out it's based on the years they have, at least that's what I do myself. I set the alarm clock and put it right next to my 4 yr old son. And I tell him that when the alarm goes off he is allowed to get up from the chair/bed whichever it's closer at "x" situation. I would say 5 min
When my 4 year old hit at school we told her if she did it again we would take all the toys in her room away. She hit again, we took all the toys away, and brought them back slowly. She never hit again.