I no longer take commissioned work, but when I did I always washed it after quilting for 3 reasons:
1) to remove any marks that might not have completely come out with spritzing
2) because I only make baby quilts & want to be sure the quilt is as clean and allergen-free as possible before sending it into a home with a little one
3) if it's going to crinkle, I want that to happen before I give it to the customer (grandparent) so they don't give it to their child (parent) who washes it the first time & thinks they somehow ruined the quilt