I also agree to not prewashing a kit. But I always use SHOUT color catchers when I do wash a quilt to prevent running of obvious colors such as reds, purples even some bright colors. But I never wash charms or fabric that is pre-cut and in strips.
I have learned the hard way, that I need to prewash fabric that has come from my LQS or a local store here in town, to remove the chemicals that leave it stiff and hard to work with, not to mention that several women on this message board are allergic to the chemicals.
Stephanie