you may want to contact the shop where you purchased the kit and ask them if they intended for the pieces to be pre-washed, usually kit's are not if they are pre-cut kits. I have made literally hundreds of quilts and many of them were made with fabrics that were not washed until the quilt was quilted and bound. i never had a quilt not turn out. i have had a couple quilts have colors bleed. it is always a good idea to at least test for color-fastness. if the fabrics don't bleed, go ahead and wait to wash. it is the batting and the amount of quilting that dictates how much shrinkage a quilt has.