Hi S A,
If you don't think that you're going to have enough time to properly study for the GMAT, then the smart choice is to push back your Test Date. There's certainly no harm in taking the GMAT as scheduled - if you're unhappy with the score result, then you can simply cancel the score (and no one, other than you, will ever have access to that result). The cost to retake the GMAT is still $250.
There are some broader questions about your situation, so it would help if you provided a bit more information about your timeline and goals:
1) How long have you studied?
2) What materials have you used?
3) How have you scored on each of your CATs (including the Quant and Verbal Scaled Scores)?
4) What is your goal score?
5) What is your current Test Date?
6) When are you planning to apply to Business School?
GMAT assassins aren't born, they're made,
Rich