I always wash my fabric before it even lands in my sewing area.
Reason: removes sizing, gives me a heads up for any bleeding fabric (wash like colors together along with one or two Color Catcher sheets), fabric might not be on straight of grain off the bolt, ironing after washing helps get it on straight of grain. Then there is the issue of importing nasties...bed bugs was a heavily discussed subject not too long ago. Then, most of the shrinkage is taken care of.
Just me, and how I do it.
Oops, just realize Judie posted the bug issue also...like minds.