I wash all red, black, dark brown, dark blues prior to using, unless it's a wall hanging. Just me. I have had some triangle cut fabrics shrink when ironing with steam. They usually shrink in the middle.
I like spray starching on the back side of the fabric, rub in into the material so it doesn't leave little white speck for me to brush off. I think your project looks better and is more accurate when ironed. Happy sewing.