The multi-wash approach is to try to get all the shrinkage out of the way before using the fabric. Hot water wash and hot dryer.
You won't be "in trouble" ... your quilt just might get more of the crinkled old fashioned look when washed, than if the fabric had been washed more often before making your quilt. Too, keep in mind that most battings are going to shrink too, unless of course, you have pre-shrunk that.