Is the question: "How do I tell my washed fabrics from my unwashed fabrics?"
If so, I fold my washed fabrics differently than the unwashed ones.
At one time, I kept the unwashed ones away from the washed ones but I got behind on my washing
I usually serge or overcast the raw edges of the fabrics before washing them (even fat quarters).
I pretty much avoid buying anything smaller than a fat quarter or 1/2 yard because I am so compulsive about prewashing.
I have - very gently - washed cut pieces, but it's a real PIDA to do so. And it gives me an even bigger pain to NOT wash them. So - a girl has got to do what she's got to do.