I'd suggest that you wait until the quilt is quilted.
If you feel that you can't wait, then fold the quilt into 1/8ths and pin it up so that it can't unfold. Wash on light /gentle setting in cold water, use whatever laundry detergent you normally use and add a couple of color catchers. Unfold to dry in the dryer or lay out to dry.
I did it that way once, but wouldn't go through the bother again.