My strategy for both the GMAT and the LSAT was to take the test just as another prep test. If you can do the tests at home, this one is exactly the same. Also, there really is nothing you can do at this point (day of). Be happy with that fact and just do your best. There are basically three things I try to do with regards to these tests to deal with anxiety:
1. Diminish the importance of the test in your mindThe day of, and the day before, ask yourself the question: What's the worst that can happen? So you flunk the test or score worse than you would have wanted. So what? The world is not going to come to an end. You can retake the test, you can postpone your applications, you can learn from your experience, etc. Unless you excel under pressure, don't hype this test up to be the make or break event of your life. It's just a test, life goes on. You're a tiny spec in an infinite universe
Of course... don't UNDER value the test either. If you don't perform with an "I don't care" attitude, don't go that far either. Find a nice middle ground.
2. Pump yourself up and go in confidentWhile as I think you should try not to think about the test much the day before and day of, still remind yourself from time to time that you are absolutely going to
kill this thing! Go into that room with confidence. Tell yourself that this test has nothing on you and that you are simply going to destroy it.
3. Know that you are prepared and don't panicYou've studied, you've prepared, you're ready for this test. Know that. Know it for a fact. You've done what you were supposed to do, now what's left is to apply it. This plays into the confidence factor. You've written prep tests, you've revised and killed questions, now just do it again. The actual test is no different, just take it as another prep. If you can do it at home or at a library or coffee shop, why not here? Also, don't panic. If a question is hard and takes more time than you would have liked, fine, just concentrate on the next one. Forget what happened in the question before, forget what happened in the section before and just concentrate on the one that you are doing right now. Who cares if you got it wrong (and who really knows if you did...)? Just hit the next one. After every section, take your break, put the last section out of your mind even if you think you sucked at it, and concentrate on the next one. It's a whole new ball game. Between sections, I made sure to go to the bathroom, have a drink, look out the window, breath, relax, tell yourself you're going to kill the next section, and then go back in relaxed, but confident. Picture what you're going to do and how you're going to feel after you get your 800 score back. It's going to be a good day!
Overall, find what works for you. The day before, many people say to take the day off and do something you enjoy and find relaxing. If this works for you, I would definitely recommend it. But if on the other hand you feel more comfortable revising the day before or day of, maybe that's what works best for you. Only you know yourself. You've taken so many tests in your life, just think what has worked for you so far and do it.
What I would recommend is to drive down to your test center a day or two before just to know how to get there. Don't get lost the day of. Leave early (account for traffic or metros breaking down) and get enough sleep the night before. Don't stay up all night thinking about the test. Put it out of your mind, tell yourself you're going to kill it, and go to bed. Some people recommend sleeping pills or what not, I've never needed it, but again, do what works for you. Don't get lost or be late on the day of the test, these are stressers that you can do without and that are easy to avoid. If you get there early, take a walk, breath, relax. It's just a test. It's not the do-all end-all event that you're making it seem like. Chill!!
Finally... even if you suck it up, cancel your score or get a crappier score than you would have liked...
It's not the end of the world! Breath, put things into perspective... It's just a test. One little test. Go home, relax, don't think about it for a couple of days and then re-assess the situation and decide what your next steps are. Will you retake? Will you go with what you have? Life goes on
Good luck!