Jeremy's right - the final 1-2 week timeframe is mostly about review and solidifying the skills you already have so that you make sure you "peak" on test day. If you're currently hovering around 600 and you want to hit 700, it's probably going to take more than the 8 days that you (now) have left. Ideally, your practice test score from a week or two before the test should be in the same range as your goal score for the real test.
If you're currently around 600 and want to get at least 630, then it's possible that you can hit that, but it's also possible that you won't.
Either way, I'd say it's in your best interest to postpone right now, unless you're willing to take the risk that you might not cross 630 in 8 days. Then, ask yourself: is your goal 650? Or is your goal 700? 700 is going to take longer and require more work, so you have to decide what you really want to do here.
Were you taking a course? Is that course over now? If so, then you're going to need to start developing your own study plan (and adapting it as you make progress). Use this article to help:
http://www.beatthegmat.com/mba/2010/02/09/developing-a-study-planOne of the things that article tells you to do is analyze a recent MGMAT practice test to determine your strengths and weaknesses. If you'd like, after you do that analysis, come back and post your findings here. Then we can help you figure out what to do and how to prioritize your time. (We need a lot of detailed data in order to help you figure out how to spend your time!)
Also, you may benefit from some additional knowledge about how to get the most out of your study. Try this article for some ideas:
http://www.beatthegmat.com/mba/2010/03/22/the-best-of-beat-the-gmat-mgmat-how-to-study-list