Generally speaking, do
less the closer you get to the exam. You know what you know. And what you don't know - you're not going to learn / master in the next 3 days.
Your goal now is to:
(1) do some* random practice in approximately the same difficulty range that you expect to see on the real test - not a ton harder or easier
(2) conduct a general review of the
most commonly tested question types / content areas (NOT a review of every last thing you could possibly see on the test; don't overload your brain)
(3) review your "game plan": how are you going to manage your timing across each section? What are you going to do if you find yourself 4+ minutes ahead or behind on time? How are you going to make good decisions about which questions to pursue and which ones to blow off (guess and move on)? Etc.
*Some = maybe 30-60 minutes a day in the last 2-3 days. Really not much! And no more than 2 hours total of anything GMAT related on the day before. 30 minutes of pratice problems. 60-90 minutes of high-level review. That's it!
Plan something relaxing / fun for the night before. Watch a favorite movie. Do something with a friend or family member who won't stress you out or constantly remind you of the test. That sort of thing. You'll still be nervous. But at least you'll be trying to distract yourself.
Also, get everything ready the night before: your ID, directions to the test center, the food and drink you want to bring, etc.
Finally, aim to get there 15-20 minutes early, just in case.
Good luck!!
