Read it as first book in first attempt.
I made 75 Hard the first book I read for my 10 pages each day as I was first attempting the program. I stumbled into it but highly recommend doing it this way. By reading the book, I understood the mental part of this program (also listen to the podcast he sends you) and this kept me honest. I failed a couple weeks into my first round by forgetting the progress pic. Not the water, not the diet, not the reading, not the workouts. The stupid pic! If I hadn't read the book, listened to the podcast, and really understood the mental aspect (part of this is the pic is for building attention to detail), I probably would have just kept going and made excuses about forgetting the pic. Instead I had to start over and am now on my second attempt. If you are going to put yourself through something like this, get the most out of it by doing it right. Listen to the podcast. Get the book. Don't sell yourself short by allowing excuses or workarounds.