My sister's quilt is the only one i've made from start to finish. I did not pre-wash, but did wash it after i was finished...Delicate, short wash, gentle rinse and hung outside to dry - no dryer...
My aunt's quilt, i also washed, but since she made it in the 50s, and it was a scrap quilt, i assume it was prewashed. Again, gentle wash and hung out to dry.