My test started early in the morning, 7:30 am, I think. I ate a good breakfast (as usual). I brought with me some energy bars and bottled water. Soda and caffeinated drinks are not for me, but you should bring a beverage that you like. I chose energy bars because in a few bites you can get up to 200 calories (or so) of a good mix of protein, carbs, and fat and I find the ones I often eat very satisfying. Choose something that you like the taste and make you feel good afterward. I did pack a lunch that I ate before I drove home after the test, but I did not bring this into the test area. I don't function well when I'm hungry so I came prepared!
I did not want to waste any time. I used the restroom in the middle of the test because I knew I would be more comfortable if I planned on that, but I wasted no time! I had time to check that I had answered everything and the answers were well blackened in. That's how it went, and I am glad a passed the first time, because it is such a long test!
Good that you are thinking ahead. Planning is important!