Now that you have a plan, the next question revolves around adaptability. Do you have to follow the plan precisely?
It probably depends on who you ask.
Those with a type “A” personality will insist you follow the workout precisely. If you miss a run, the world will come crashing down. It's a moot point, though, because your run should be at the top of your list of the other 498 things you have to do each day.
As you probably guessed, I'm not really a list-making kind of person. I'm more of a realist. I'm also guessing you're not really a type "A" personality, either. After all, you are reading a book with a ridiculous title written by a mediocre runner.
If you miss a run, it's not a big deal. In fact, taking a break occasionally gives your body time to heal. If you DO miss a workout, just move on to the next one on the schedule.
Just don't make it a habit.