Everything's better with Magitek
The reason I don't equip the Kaiser right away is because it doesn't seem to make a difference in the opera battles (rats and Ultros), so it isn't really needed until Number 128. I hadn't thought about delaying party management until Jidoor, though, and it wouldn't hurt to equip the Kaiser earlier. My own preference is to do menu stuff right after cutscenes if possible; that way I can memorize the menu changes during the cutscene and then carry them out before I get distracted by other things.