I assume from your post that you have the home study course. During the course you photo read both books.
I learned the 3rd edition book in about 90 minutes were my normal reading speed and comprehension would of taken me a few days with lots of re-reading. That is BEFORE this course.
I fully understand and comprehend the book using the Photo Reading techniques, even after a few days of not touching it since the initial learning.
To answer your question start the tapes and do all the exercises. around tape 3 or 4 you completely photo read the book and believe me you will understand it front and back when you are done.
What helps is that everything in the book is in the course so you hear everything along with absorbing the book. By tape 5 you will pretty much be on your way.
I listened and participated up to tape 4 then I took a couple days off, though I intended to get back on it the following day it didn't happen.
Breaking up the program into seperate sessions instead of listening straight through will help you I believe more than just one long session.