I am old school and was taught to always wash my fabrics (obviously can't with pre-cuts) I either dry until damp or store them in a bag damp while I dry iron it all. Never had a problem doing it this way as far as shrinkage is concerned anyway, a few years ago before fabric was the cost that it is today I bought some fabric from a well-known designer that cost $10.00 a yard it did things I've never seen before, it frayed like nothing I ever had and became so wonky that the amount of shrinkage was about 2 1/4 inches. Still have it the shop wouldn't take it back because it had been washed, the manager told me she would get a piece of it and if it happened to her she would give me a refund but she never did! Needless to say they lost my business.