Hospital BAG checklist

Hi mommies! When do you guys start preparing for your hospital bag? And what do you need to prepare in it for both mummy and baby? Ps: if it was as easy as taking care of kittens (preparing their stuffs etc), i wouldn't have an issue since my boys grow up well HAHAHA! but when it comes to babies, i need your expertise. Hehe, do help a sister out :) thanks in advance