I recently finished pieceing a queen size quilt top. I was so excited to start quilting it that I forgot to prewash the fannel backing that I'm going to use and I've already cut all the fabric in 12 1/2 inch squares. I know it's going to shrink and ruin all my hard work I did on the top. Is it to late to wash the flannel? Will my squares fray much. Should I go ahead and piece the backing together and then wash? What should I do? Any remedy for my blunder?