Not to demoralize you, but if you are not hitting close to 600 in your preps (2 or 3 days before the exam) then don't expect any miracles on the real exam.
Long story short I recommend the following:
1. Are you unable to complete the test of just get too many questions wrong?
2. If you are getting too many questions wrong do the following
a) Identify your weak areas.
b) Pick up OG 11
or OG 12
and work out problems in that area. MGMAT probably has a master list that classifies all questions by their class.
c) Practice OG questions, but the key is to read the explanations for the correct and incorrect questions alike. Understand what you did wrong and why and take some corrective action to
not repeat that mistake.
3. If your strategy is faulty, then search for Run Purewal's posts on MGMAT he has some excellent advice. His advise in a nutshell: have a time-plan and a contingency strategy. In an excel sheet note how much time you can spend per question (both sections). Also, look analyze the verbal section in GMAT Prep - the real GMAT follows the question order pretty closely.