Just stay calm, practice the areas that are weak, and basically RELAX (again).. 99.9% of the people perform better when they are relaxed, tension-free and when they do not have any pressure on them. The GMAT is unlike the FINALS most of us are used to from college in the sense that you can take it again if you do not perform well the first time. Take it as a challenge, a fight against you and the GMAT, and look at it from the prospective that ONLY YOU CAN WIN!, because you have the privilege of rescheduling as many FIGHTS with the GMAT as you want, and the GMAT is in a LOSE-LOSE situation ;-(..
If you are weak in quant, and can point out certain areas of weakness (DS for example, try going over some of the strategies with regards to DS, practice DS from various sources (last 20-30 OG13 questions are quite good). You can go over VIDEOS from RON (MGMAT) for strategy on test day etc. All in all, do not spend more then 3-5 hours a day on prep, and try to be relaxed and sleep well in the final 2-3 days before G DAY.
You may view David@VeritasPrep's posts here:-
https://www.beatthegmat.com/mayday-mayda ... 39295.html
Best of Luck !
"When you want to succeed as bad as you want to breathe, then you'll be successful." - Eric Thomas