When you look at the F&P tute, the illustration where you begin cutting is flat but it's actually a tube at that point. It's easy to do once you try it. Your first time can be a little frustrating but hang in there, this technique is SO worth the effort. :D
I always make much more than I'll need because if I want to add it as an embellishment to match (like pillowcases) or for a completely different project, it's already done. I tend to use bright colors that will easily mix with other projects rather than match the background fabrics but if you really like it, make a lot & skip this step next time.
I store mine on scrap cardboard that sometimes comes in FQs or pieces of cereal box cut into rectangles and just wrap my leftovers. I also press in half before I cut to size which makes it really easy to apply by machine with an invisible stitch and roll to the back where I blind stitch & store for future projects.