If you haven't taken the test at all, then I would suggest you to work on official problems for the rest of the days, maximize your strengths and take the test, but be prepared to face a score less than 700. It is very difficult to achieve 700 in such a short time given your GMATPrep scores, while it is not impossible.

Otherwise reschedule the test by a month or 45 to 50 days. You still need lot to learn in both quant and verbal. MGMAT quant is cumbersome, while GMAT quant is full of nuances and traps. MGMAT verbal is a bit more of rule based, while GMAT verbal is not. Use the MGMAT reports, identify weak areas and work on them. Solve more OG problems, repeat them even if you have already solved them, you can repeat them n number of times. Verbal part is quite different. Do not stick to one strategy for a long time, if your strategy is time consuming and less accurate, then you should switch over to new strategies. CR and RC are both similar in this aspect, you need practice questions to learn the right strategy. After that even if you don't practice regularly, you can solve them easily. Stick to official problems.

Rescheduling may seem to be a good option, but improving from low 600s to 700+ sometimes take more than 50 days and you shouldn't be in a position to reschedule again, so the best bet would be to take the test once (if you haven't taken at all) and then go for a retake once you feel ready instead of rescheduling the test till you get ready.