First things first. It's very unlikely that you are going to go from a 600 to a 700 in three weeks. I know that's not what you want to hear, but it's true, so I want you to know that right now rather than two weeks and 6 days from now when the test is the next day and your latest practice test isn't at 700. Or, worse, three weeks from now after you've taken the test and haven't gotten that 700.
(Yes, I saw that you're planning to take 10 days off. Doesn't matter - this isn't about just cramming a certain amount of practice in.)
So. Here's what we do. When you're still this far from your goal score, you shouldn't even be thinking about a deadline to take the test. You can have a vague idea in mind, sure, but your score has to be closer before you can think about setting a test date.
You mention major time management issues. You can fix that, but it's going to take some time and hard work. Most people who have major timing issues need at least 4 to 6 weeks to fix the problems. Read this article and start working on the techniques it describes:
http://www.manhattangmat.com/blog/index ... anagement/Next, let's identify your specific weaknesses so that we can come up with a good plan. Read the below article and do the analysis described (on your most recent MGMAT CAT):
http://www.manhattangmat.com/blog/index ... ice-tests/Then come back here and share your analysis (not just the raw data! your actual analysis of the data), and we'll talk about where to go from there.
Finally, you mentioned committing the same kinds of errors over and over sometimes. Read this article for help:
http://www.manhattangmat.com/articles/error-log.cfm