Starting with the next opponent in turn order (or the active player, if that player is one of your opponents), each opponent in turn order decides whether or not to copy the spell and, if they do, whether or not to choose new targets. Then, if that player did choose to copy the spell, the copy is put onto the stack. Finally, you copy that spell at least once (hopefully more, if the mayhem was tempting enough) and choose new targets for your copies if you wish. This means that your copies of the spell will resolve first, followed by the copies created by your opponents in the opposite order in which they were created.