I usually mark my top before I sandwich it, because the surface is flatter, and will not get distorted with the batting and backing. And I don't use the purple marker because it disappears too quickly -- 1 to 2 days usually. I use the blue marker that washes out, or the new ultra clean washable crayola markers. I like to wash my finished quilts anyway, before I gift them. I love the look and feel of the washed quilt, plus I can "catch" any bleeds with color catchers. I don't prewash my fabrics if I'm using precuts, which I've been using alot lately.