Assuming that you have studied and prepared adequately for the exam, it seems that you're in decent shape. However, I do agree with whiplash2411. The best predictor of your actual performance is the GMATPrep. It's also the best test preparation, in terms of CAT practice.
And make sure to take the test under the same conditions as the real thing. That means a computer desk and chair, timed conditions with breaks, a quiet atmosphere, and (ideally) use a test simulation booklet
and pen. I would even recommend wearing what you will have on during the actual test! Practice tests in a t-shirt, shorts, and no shoes, for instance, is a little too comfortable.
From what I understand, though, the verbal score decreases rather quickly. If you answer incorrectly the experimental questions, then no big deal. However, I don't think that test prep companies (Manhattan, Kaplan
, Princeton, etc.) incorporate experimental questions into their CAT simulations. Again, though, the previous post makes a good point about the algorithm.