There are two ways to approach pleating. Typically traditional pleats have a 5/8" to 3/4" reveal.
1) If you are limited by length of material, then mark the aprons, one on each end of the material. Then start marking off the pleats until you reach the apron with the appropriate spacing from the last pleat to the apron edge. You can even do this before you rip the material.

2) Use the method in the book. (Chapter 8)