You have raised three separate issues.
1) How to maintain proper pacing
2) How to read faster
3) How to predict your current test performance
I recommend you tackle these issues separately.
Proper pacing typically requires that you have a published and fixed timing rubric that you follow to know whether you are ahead-of or behind schedule. I suggest you divide the verbal section into 4 even periods and attempt to answer 10 questions in each period. (Plus an extra question in the 1st period to equal 41 total.) At the end of each timing quartile, if you are behind, guess until you are on schedule. (Note, this is VERY hard to do. You need iron discipline to maintain good pacing. If you can do it, however, you the reward is worth the effort.
Reading faster is the hardest of the three things to accomplish. You can help yourself by taking notes according to where the GMAT typically places valuable information. I don't have room here to explain the details, but in short, there are two types of passages: long and short. If you want to understand where the important information is kept, you can read about it in the MGMAT guide book dedicated to RC. It's cheap. You can also increase your reading speed by drilling on speed. Try reading faster than you feel comfortable reading for three passages, then switch back to comfortable. You can expect to read noticeably faster by doing this exercise.
Don't try to predict your current test performance. It's not effective, not useful, and not worth it. Just keep your head to the grind stone and pound it out. You can figure out your score at the end.
Enjoy,
T
