If you only use the fabrics from the kit and it is for your use, then why wash? UNLESS there is an intense fabric that has the potential of bleeding. Even still, with the option of using Retayne and color catchers in the laundry you should be safe.
My personal rule on a prject is that either ALL is washed or ALL is unwashed. I don't mix because I don't know how the individual fabrics might shrink.