What happens if

Hi…I’m currently working at a bushiban and I’m not happy there. I’ve been offered a position at a different school which I want to take, but I’m worried about my ARC. If I jump ship, my ARC will be cancelled - I don’t know if that will happen right away or not. My new job is offering me the ARC, but I want to know if I have to do anything from a legal standpoint if there is a gap between the new one and the old one. Otherwise, if there is no gap, and I apply for the new ARC while the old one is still valid, is that a problem???
Any advice would be greatly appreciated,