I would not wash it til you are done. My very first quilt ever, about 12 years ago, was in flannel, 3 1/2 inch squares, trip around the world. Why in the world the teacher chose that for us is beyond me, but, it was a great learning experience. We used the flannel straight from the store. No prewashing. I used warm and natural for the batting, and flannel for the backing. took it home and washed it. It is 12 years old, on the granddaughters bed still (under a bigger quilt), and has been washed a gazillion times and it still looks good and she still loves it.