I just retook my exam today. I don't know how you have been prepping, and it's pretty much too late for me to tell you how I studied. But I definitely got above 17s on all my scores, and I just went over a few random math problems right before I went in to take the exam. Be sure to go over the trig stuff, and know how to find angles. I came across a lot of those today, and lots of wordy problems, that were really hard to solve fast- and math is my strong point.
As far as Reading Comp. goes, I didn't study this at all! Yet, scored a 20 on it. Maybe luck, but you'll be fine, if you can find the answer to each Q fast. Find it, and move on. I took a few deep breaths and closed my eyes for 5 seconds, then proceeded to work through this section.
Good luck!