This is almost my same circumstance right now. I have a new adopted baby in our group of friends. So I decided for his first quilt I would purchase the new blue fabric group from Connecting Threads and make the disappearing hourglass quilt that I have been wanting to try. So I purchased a layer cake and 1.5 yards of the white from the line. I ironed and starched the layer cakes and have starched and cut the white into the matching 10" sq. So everything is now 10 sq and stiffly starched due to the bias cuts. I figure if they shrink or whatever, they will all do it the same way, time, amount, etc. HTH
Be sure to post pics when you are done.