I'm sorry that you're struggling with the test. If it makes you feel any better, it's very common for people to "hit a wall" at certain points during their study. The good news is that you've recognized it and are asking for help. :)
You've stalled out around 600 and want around a 650, and you mention timing issues. Timing problems typically take a minimum of 3 weeks to resolve and usually more like 4 to 6. In other words, you're almost certainly going to need more time - so your best bet is to postpone your test.
You also mention that you'll "see" the approaches afterwards, when you read the explanations, but you don't know how to make the connections while looking at the questions for the first time. So that's another level of your study that needs to be refined.
I'm guessing that, so far, you've mostly concentrated on learning the concepts / content, but you haven't spent much time actually analyzing how questions are constructed, how they disguise what they're asking, how they actually make things hard in the moment, even though you do understand the solution afterwards. This, again, is going to take some time to learn / master. You're going to need to give yourself more time before you take this test.
Read this:
http://www.manhattangmat.com/blog/index ... -the-gmat/Pay particular attention to the How to learn section and also the material on time management. Start thinking about how you need to change your study approach in order to get better at recognizing what these questions are really asking / telling you.
Then, use the below to analyze your most recent MGMAT CAT(s):
http://www.manhattangmat.com/blog/index ... ice-tests/Finally, come back here and tell us the results of your analysis and what you think you should do based on that analysis. We'll tell you whether we agree and advise you further. (Note: do share an analysis with us, not just the raw data. Part of getting better is developing your ability to analyze your results - figure out what they mean and what you think you should do about them!)
I'll also just comment on wfzhang20's approach. I know you already know that this approach is non-ideal, wfzhang20. Given your starting point, though, and the fact that you even contemplated doing this in a week, you're the kind of person who just does well on these tests, right? Most people can't follow that approach. :)