It's best to check if your Fair has any rules regarding this.
All of my entries for the Fairs are made for my own purposes first ... and if they fit the classes at the Fairs, and I feel they are up to snuff ...... then they might get entered. So that means, all of my fabrics are washed first, before I assemble them into a quilt, tabletopper, etc.
I press well and starch all thru the process ... my fabrics turn out pretty fresh and crisp, so I'm not sure why your concern. Actually, to be honest, many of the fabrics look far better after they've been worked with, than in the original unwashed and as-is purchased state. At least that's what I see with the ones I do.
Any of the Fairs that I have shown at you must NOT wash your item after it has been made.
Again ... check your local rules!