Any pointers on how I should spend the next two nights?

Dude my experience is very different. I decided to take the day off before the test day. studied some formulas and that was it. but since i had built the habit of doing some thing all the time (u know office and study doesnt leaves any of ur time slots vacant) and i had nothing to do on that sunday (my test was on monday), so this stressed me a bit. The result was not that good either. my Official GMAT score was only 660 wheras on the saturday night i had scored 710 on the official practice test. and my scores were constantly improving. Immediately after seeing my 660, i realized that had i done a test in the evening, it would have calmed my nerves.
But all said, every one is different and u need to do what suits and calms u. May be u could take the whole day off and perfomr better.
Anyway wish u luck dude.
Dont forget to share ur score with us.

Do all to spend an excellent night before !

Good Luck