Hi J.,
I used that book and am now 13 weeks pregnant and, after having two girls already, we were told on Tuesday at a scan that it looked like it might be the boy we were trying for!! It's a bit early to say for sure but I have my fingers crossed. Obviously a healthy baby is our first priority but there's no harm in hoping to having a boy ..... we'll love a little girl too if that's what my bump turns out to be ;)
If I were you I'd be sure to take the time to find out how long your cycle is (mine changed from always being 28 days to being 31 days) and then it'll be easier to find ovulation. I also used the 'clear blue' ovulation test kit that cost about $20 and had about 7 tests in it.
So, I'd say follow the recommendations in the book and have fun!!
Good luck,
M..