Hi Matt,
As a general rule, Business Schools don't care if you take the GMAT more than once. Since you're already scheduled to take the GMAT today, there's really no harm in doing so. From what you've described, with just 2 weeks of study, you're probably not going to hit your score goals - but that's okay. Take this as a learning experience.
Most Test Takers spend 3 months (or more) on the study process to hit their respective "peak" scores. During that time, it's common to spend 10-15 hours per week (or more) on the process. You should keep that in mind as you plan out the next few months.
When you take the GMAT today, it's important that you try to remember the SCALED SCORES for the Quant and Verbal sections (assuming that you end up canceling your scores). THAT data is important - it'll give me some data about your performance in those 2 sections, so I'll be able to offer you some tactical advice later on.
Is there any particular reason why you scheduled your Test Date so "soon?"
GMAT assassins aren't born, they're made,
Rich