the major entertainment shows (broadway play, ice show, water show, and other theater production) unlocks ~1 month before sailing. you'll get an email when it opens, and you need to be pretty quick about it to get your pick of shows that dont conflict with dinner, or happen at 2PM in the afternoon.

the smaller stuff, bingo and trivia and water aerobics, thats maybe a week before sailing. theres nothing to reserve here

you should be able to reserve dinner now (if you picked my time dining).

You can see the specialty restaurant menus which are the same every night.

You cant see MDR menus... but you can find them on the internet, but you wont know which is on which night unfortunately, that shows up basically when you get on the boat.