I always wash fabric first then iron if it's yardage, fatquarters or whatever. I am careful with strips or small pieces. I was taught all the usual rules too. If you ever watch Missouri Quilt Company videos on UTube, you'll see Jenny iron. Can't ever remember seeing her press and she turns out beautiful quilts. She also makes it look so easy.
By all means iron but that doesn't mean drag the iron so hard that you do distort the fabric. Just as you would do ironing the family's clothes. If you should comes across some stubborn creases press those and use some steam.
All the best and Happy Quilting.