Welcome from Ontario, Canada. Yep, most people don't pre-wash their pre-cuts because they fray. Finish quilting and binding and then wash. You will get a little shrinkage but that gives you that nice comfy look. If you prefer a like new appearance, wash and dry until damp and then block out flat to finish drying. Sounds like you are well on your way and you might enjoy Jenny Doan's videos for the Missouri Star Quilt Co on Utube.