It's telling you not to create a deficit in the beginning so that you have a good base to start with. ie… do what you think/calculate as maintenance and follow that for a bit to A) see if it IS maintenance, and B) to see what your results are at maintenance before cutting cals or increasing cals.
Since one of the ways to use this book is for body recomposition (losing fat and gaining muscle), eating maintenance or just under by a little bit is actually one of the ways to accomplish that. Your weight won't change really, but can see results in the size and shape of your body.
So, start at what you've calculated your maintenance to be and weigh and track your food. After a bit you'll see where your weight is trending and know if/how to adjust.
It's a few weeks/couple months out of your life… it ain't gonna kill ya.
