I’ve found over the years that using a time-out as a solution for aggression is rarely productive. I also feel that the notion of it lasting one minute for each year they’ve been on the planet is very arbitrary. I understand the motivation behind this – it’s not a great idea to leave a child in a time-out for long periods of time. It becomes punitive in a way that is unfair.
Instead, I direct the power to the child, while still keeping my authority. If, for example, they’ve taken a toy from another child, even if that other child isn’t particularly upset, I ask him or her if I have to give it back, or can they? More times than not, they will do on their own. Maybe not happily, but they will hand it over. Of course there are variations on this theme that could fill volumes, but it is basically the same idea every time.