Do most people arrive to ODS the day before, just to ensure you arrive on-time?
Any benefit to getting uniform items before reporting? If so, what would be the best bet?
Any items not on the official list that one should plan to bring?
I've read as much as I can find by searching around, and reading everyone's comments over the years. I know there will always be some "unknowns", which is probably for the best, but would like to gain as much knowledge prior to reporting as I possibly can.
The majority of my class arrived the day before including myself (and another ensign from my unit - he browses AW in fact, yo man hope all is well! You owe me some whiskey!).
You can absolutely bring uniform items ahead of time, but if they are incorrect or not serviceable (as determined by staff) you'll have to purchase new items. If you're not prior Navy I wouldn't bother. I brought some Type 3's and PT gear, but only because I was already drilling and purchased it for that purpose.
If you're prior service (I was enlisted AF for example) you need to look up and bring authorized ribbons and medals (large ones not mini).
I'd have to look at the official list, but honestly everything you "need" is there. In fact the "free store" (which is a literal large storage room) is FILLED with items left behind by previous classes. This includes blankets, irons, soap, shampoo, fans, pillows, rulers, pencils, etc .. Also keep in mind anything extra you bring you need to store. I did enjoy having my own set of pens and a notepad (especially if you volunteer as student leadership). If you have any specific items in mind .. let me know and I'll happily weigh in.
Let me level with you, unknowns are good, you need to embrace it. You're going to walk into a lot of unknowns at your first unit, wardroom, billet, etc. If you want to get ahead .. learn Anchors Aweigh, Sailor's Creed, Navy and Marine Ranks (both enlisted and officer), 11 General Orders of the Sentry, and Code of Conduct verbatim. You'll be required to learn a handful of other things as well, but if you can lock that stuff up prior to arrival you'll be good to go.
Best of luck! You'll certainly meet a lot of new folks and make a lot of friends.