I am making my grandson a rag quilt with denim on the back and homespun on the front. SHould I wash the homespun first, or wait until the quilt is done ? Never used homespun before, so not sure how it behaves

Is the denim new or recycled? If its recycled then yes, prewash. Homespun usually shrinks a good bit. If they are all new fabrics guess you really wouldn't have to wash anything before. Denim bleeds so much but I don't think I have had homespun bleed much.

wash it gently..it frayes like crazy. better still, sew around the edges of the yardage..

Oh Yeah, I usually serge the ends before I wash.

i worked with it once< i love the way it looks
would no work with it again

I'd be sure both fabrics were pre-washed because of shrinkage. I bast raw edges to limit fraying. Extra work but worth it to me.