It is strictly up to you and how you prefer to wash cotton items. The only advantage is to keep the wrinkles from being as hard set and easier to press out before you cut. When I do laundry I do use a half sheet of Bounce in the dryer. I do not know if this next comment is applicable to making a rag quilt; but, when I use flannel on the back of a quilt I pre-wash it in hot water twice before I use it because flannel can shrink 4 or 5 percent.