Because of sensitivity to whatever it takes to make fabric beautiful I previously prewashed. Lately experimented with soaking in hot water, agitate a short time, and spin. That seems to take out what ever bothers me and takes less time. Fat quarters do fine either way but charms would be better done by hand. Jelly Rolls best if left alone. The only quilt I made without prewash was a one block wonder and while it was nice working with unwashed fabric my eyes and skin were really glad when the quilt was done. Have fun with the gift of extra fabric.