This is a really smart thread. Very good subject that I don't think many people think about.
*******IT IS ABSOLUTELY IMPERATIVE THAT YOU VISIT YOUR PROMETRIC CENTER BEFORE YOUR TEST DAY***********
Consider: you want to have as clear a mind as possible going into your test. This means that you want to have to process as little extraneous information as possible. Even if you just walk inside and get a look around, that's one less thing that you'll have to think about and process the morning of your test day. I went to mine the day before and got a look at the lobby, saw where the lockers were, went to the bathroom, and spoke to one of the girls there at length about what to expect when i showed up there the next day. She was even nice enough to let me see the "scratch" sheets and pen i'd be getting (the pens my testing center used were awesome: they were like the super-fine point sharpies with the tip that's almost all metal).
***MAKE A POINT TO PINPOINT THE LOCATIONS OF ALL THE CLOCKS IN THE TESTING CENTER AND JUST CHECK TO MAKE SURE THEY'RE ALL RELATIVELY SYNCHRONIZED.*** (this sounds kind of ridiculous and overkill, and it might be, but better safe than sorry. you'll see why in a minute)
my point is: this is ALL stuff that i was able to process the day before i took my DAT and thus didn't have to even THINK about the morning of. remember: you want to be as clear-headed as possible, so take care of as many unnecessary trivialities as possible the day before. this also includes setting out your clothes the night before and even getting your food for the morning ready the night before (i set my granola bar and banana out ont he counter and filled up my insulated water bottle and had it all laid out right next to my keys. i even poured my cereal for breakfast into a bowl and left it sitting out on the counter overnight).
i'm sure the little rules vary by testing center, but here were the basic rules of mine:
1) absolutely NOTHING on your person at all, not even a watch (this will be meaningful in a minute). there are lockers with keys that you can stow all your stuff into. the girl had me turn out all my pockets to show i had nothing in them and even ran a metal-detector wand over me. she actually almost made me leave my wedding ring, but after i took it off and showed her there wasn't anything inscribed in it she was cool with it. basically, the only things you'll have with you when you walk into the testing room are your scratch paper/pen, 2 ID's, and a key to your locker.
2) earplugs WERE allowed, but not provided. i didn't ask if they had to be new and unopened since i never used any. they had headsets.
3) i got 2 pieces of scratch paper. i was able to get as much more as i wanted, but had to turn one in for a new one. therefore, you are only allowed two sheets at a time at your station. you can use as many as you want, but you have to rotate them. so if you're going to use one to jot down notes and reminders and equations, just make sure you use the other one for your science/PAT half and then you can trade that one out for a new one over the break. BUT I STRONGLY SUGGEST YOU CHECK ON THIS POLICY WITH YOUR TESTING CENTER. yours may be different.
4) breaks: you can leave the testing ROOM anytime you'd like, but you can only leave the testing CENTER during the scheduled break after PAT. also, you aren't allowed to access your locker during an "unscheduled" break. so basically you're only allowed to leave during the test to go to the bathroom or get a drink of water.
DURING your 15-min break, you can do whatever you want: take a ****, grab a burger, go for a walk, or try and cram whatever crap you think might help you from your crib notes in your car or locker. BUT (and this is a big but), it was made clear to me that once i signed back in to re-enter the testing room during my break, even if i didn't end my break on the computer, i could not access my locker or leave the building again. in other words, you can't run out to your car and memorize the pythagorean theorem, run back to your station and jot it down, go back to your car to look up the trig function relationships, go back in and jot those down, blah blah blah. so basically they'll give you a chance, but you only get one. in all fairness (to you as the tester), it's way better that the science section is administered first since that's the info that requires the most rote memorization.
so as far as not having your watch, i'm sure a lot of you (like me) have been working on your timing. depending on how you've prepared, when you take your test, you may find that you finish a section with a considerable amount of time left. (little tidbit: if you even THINK that you might have to go to the bathroom, i suggest going. i heard once that the urge of having to go to the restroom during a high-intensity situation can distract as much as 40% of your cognitive focus from the task at hand.) so if you do decide to run out of the testing room to pee or just get up and stretch and do some knee lifts to get the blood flowing again (which is a great way to rejuvenate your brain), obviously check to see how much time you have left and as soon as you leave the testing room, find a clock to mark the time. my testing center luckily had one right above the door to enter the room so all i had to do was leave the testing room, turn around and look up. also, someone should tell you the time when you sign out (since you have to sign in and out and mark the time every time you go in/out of the room). just bear in mind that the whole sign out/sign in procedure could take as much as a minute and maybe even more if someone is in front of you. this way, you can go do whatever and check the time on any clocks around so you don't get caught short on time. i allotted myself a minute to sign out/in and then wanted another minute to be able to sit down and breathe and get my mind back into focus mode before i started my next section.
so, kinda long-winded, i know...but hopefully helpful.