I know many quilters and most have a strong opinion about whether to pre-wash fabrics before making a quilt. I'm a "don't bother" kind of girl for two reasons:
1 - It's an extra step that requires too much time & energy (wash, dry, iron, refold …)
2 - I love quilts with that "oldy-worldy" look, even if they're brand new. And the best (only?) way to get that look is to wash the quilt in warm and dry on high after making it with non-preshrunk fabric.