Ok, don't or do prewash according to whether you like the crinkly look or not?????????? The first quilt I made I did not prewash and one of the colors ran horribly!!! I used a color grabber and ran it through the washer several times until it was more or less under control.
Now I prewash everything as soon as I bring it home. I begin with putting suspecious fabrics (deep reds, or other very dark colors) into a bin of very hot water. If it bleeds badly I soak it in cold water and salt. No more surprises for me, thank you. Some of you people are very daring.