Hi poqd,
A 670 is a really strong first performance (the national average on the Official GMAT tends to hover around 540-550), so this is a good sign. The fact that you've already identified some silly mistakes (that you should be able to fix) is also a good sign.
I have a few questions about your plans and how you took this CAT:
1) Have you scheduled your Official GMAT yet? If so, then when is it and at what time of day?
2) Did you take the ENTIRE practice CAT (including the Essay and IR sections)? If not, then you didn't complete a full test, so you didn't have to deal with the common endurance, fatigue and pacing issues that affect most people on Test Day. This would mean that your scores are likely "inflated."
Most Test Takers spend 3 months (or more) on their studies, but there are always exceptions (and you might be one of the exceptions). With these starting scores, you have a greater opportunity to pick up points in the Verbal section than in the Quant section, but there are still points to be had in the Quant section too, so you'll have to put some energy into both areas.
If you're on a compressed time-frame, then you should use the books as you see fit for the next week (you'll want to focus more on Verbal though) and then take a FULL-LENGTH CAT. Try to make that CAT as realistic as possible (take the FULL CAT, take it at the same time of day as your Official GMAT, in a quiet environment, etc.), then report back here with your scores. That data will give us a good idea of what you'll need to work on next and how close you really are to your goal.
GMAT assassins aren't born, they're made,
Rich