Pack your things in a SMALL bag - like the one that can go under an airline seat.
You will have problems digging through a big bag on the floor when you are cut in half.
Put inside:
PAINKILLERS (unless you have medical reason not to use you can mix paracetamol and ibuprofene to cover you whole day. My hospital was shit on getting painkillers out).
Your gown (don't do py as trousers are too much faf)
Some kind of thin robe (if you do not change from hospital gown first day so it will cover your bum. Ask me why I know this...)
Panties, like big ones you wore during pregnancy
Incontinence pads
Slippers and phone charger
Water bottle for drinking and getting baby cotton wipes wet
All for the baby bcs again - you will need it within arms reach: Baby nappies, cotton wipes and wet wippes, some kind of ready to feed formula with throw away tits - I used aptamil mini botttles (in case you have problems breastfeeding and your hospital cows refuse to feed the baby)
Clothes for the baby - long sleeves and overalls, some sort of blanket. Newborns do get cold quickly.
Comb and basic toletries so you can wash yourself. Towel
Something to go home in
If you want to pack multiple items and susspect longer stay break all in two bags so each got the same items and you can just ask partner or nurse to swap them.
Good luck, hope you amd bub are out the next day :)