I'm a total novice so I know it's not the proper answer but I would just mess with one long strip or hunk the width of the fabric and cut blocks or strips from that. I am just learning to use the rotary cutter so a lot of times I still trace blocks. I'm practicing with the rotary cutter but I shake a lot so I always seem to push the ruler out of wack. If you don't want to use the fabric for anything else you don't have to worry about using every square inch and a smaller section is easier to to iron and handle all the way around. Good luck.
