GMAT Strategy

I am in a little conundrum thinkin when I should sit for the test. I am tentatively planning in about a month from now with the opportunity to potentially take it the following month if necessary. My other option is to put it off into early January, but then I will have to wait at least six months if I need to retake it because of the CFA starting up again. I took a few MGMAT CATS and scored 600 (close to a month ago) and 590 (several weeks ago). I feel much more confident after doing a few hundred more practice problems, but still feel I could use a little work.

Verbal seems to be my strength:

Reading Comprehension - Confident (close to 100% hit rate); probably will not study

Critical Reasoning - Completed OG problems and looked at MGMAT book which did not seem to help; not sure how to study for this effectively

Sentence Correction - Used MGMAT SC Guide (helpful but difficult to get concepts to stick); probably weakest section in Verbal with about a 70% hit rate; thinking of reviewing old problems maybe

Quant is definitely my weaker area but it has been steadily improving (70% hit rate maybe):

Problem Solving - Improving
Data Sufficiency - Improving

Should I take an actual GMATPrep test and see where I sit? I was planning on waiting a few weeks but maybe this could give me a guideline? I definitely want to get over a 700 for sure with an 80% in Quant if possible. Any suggestions are greatly appreciated.