I always pre-wash. If I don't, I have a nasty allergic reaction to the fabric while cutting and sewing.
I also pre-wash/dry fabric in case there are bugs or bug eggs that may be clinging to the fabric. A store can be clean and tidy and show no evidence of bugs/pests, but the fabrics traveled a long way before it got to the store. It could have picked up undesirable passengers on the way. Lastly, I pre-wash because it's very easy for a customer to transfer bed bugs to fabric while browsing in the fabric store. Bed bugs are notoriously difficult to get rid of, so why take a chance?
I pre-wash using cold water, unscented laundry detergent, no softener, on a regular cycle. Then the fabric goes into the dryer (no softener fabric sheets) at high heat as that is supposed to kill any bugs that might have made it through the washing cycle.
When it is done drying, I immediately take it out and fold it to decrease wrinkling. Once washed, dried and folded, I use a thin strip of fabric to "tie"the folded yardage, and add a label to the tie that includes the length and width of the fabric.
When I'm ready to use the fabric, I iron it.