A.H.
I am not familiar with that book or author. However, I would highly recommend purchasing a fertility monitor. My husband and I had some difficulty getting pregnant with our first child. We did some fertility treatments with no success and finally became pregnant on our own. The second time around I used a fertility monitor. We started trying six months after my son was born because we didn't know how long we would have to try for a second baby. I was pregnant within 2 months!! Good luck!
A.