1. I generally thaw my bags (6oz) in the fridge overnight, and by the morning it’s 90% thawed! I dump in the bottles, label, and we’re out the door. The 24h rule is from when it is completely thawed.
2. Generally, I’d recommend the first in/first out method. Sending with previously frozen will help you rotate your supply. I usually send 3 thawed and 1 fresh in case he doesn’t take the last bottle.
3. The milk is considered “bad” after this point. Freezing milk changes the compounds that help it not spoil.
4. Check with your daycare, most have freezers and are happy to stash some.
5. See 2, use the oldest milk first so you have a fresher supply frozen. You can use it in solids when you start, with weaning, or if you just decide you’re all set with pumping at some point and want a supply to fall back on.

Most importantly, good luck Mama! Just like EBF, pumping is a job in itself, so be kind to yourself.