Honestly, I think I would consider postponing the test by about 2 weeks if I were in your shoes, but it's not unheard of to really kick up the pace and improve your experience. I would suggest two things from a practical stand point if you don't wish to postpone.
1) Review why your getting quant problems wrong. Is it lack of knowledge on certain kinds of questions? ie. DS, or problem solving. Or maybe your knowledge of probability, permutations, combinations is in need of pure focused learning. In this case, I would seriously consider purchasing the $27 study guide from
https://www.deltacourse.com. They are focused on the math part of the GMAT. Really good.
2) Review and go through your questions differently. Follow a more disciplined and more active approach to how your doing the questions.
For example, do the questions in a quant section, note which ones you are getting wrong and why. Look for trends. you can follow one persons success plan from my web site at daveformba.blogspot.com. I have a journal in my blog on how to be more structured in your approach
https://daveformba.blogspot.com/2004/06/good-info-from-someone-who-got-760-on.html
Daveformba