im repainting an old crappy guitar ive got just becuase ive go tnothing else better to do

anyways ive got it all painted and how i want it, i just have to clear coat it. how long do i need to wait before i put clear on and what would happen if i put it on too early? thanks
leave it atleast 24hours, personally i would leave it a few days, if you pit it on too early it would more than likely pull off the undercoat