Prewashing is optional with the majority of modern fabrics. Ironing is always necessary, regardless of whether the fabric has any wrinkles in it. I'd press them with steam & starch now & touch up any pieces that look too out of whack once it's ironed. I've tried to just power through mistakes myself & have regretted it later (and I am far from being a quilt perfectionist). Pressing & trimming up all those blocks now really will save you a world a problems as you go along, but try not to beat yourself up for it. We've all learned from our past choices & next time you will do it differently.
