For me I cut however much fabric I think I need for the project and maybe just a little more in case I miscut, starch it, press when dry and then do my cutting. I find ithelps with the fraying and distortion. When I get my blocks done I do a light steam pressing to set all the seams flat, then I start to assemble my blocks together. I had my old kitchen metal sink/faucet installed down here so that I could use it for cleaning paint brushes at that time and then starching my fabrics. I added a large dowel rod above the sink and keep skirt type hangers there to hang my starched fabrics to dry over the sink as it can caught any drips. I use a dishpan to dip my fabrics into, wring them out as best I can and then hang them up.
If I'm using pre-cuts, I'll starch after I get the block put together. I spray the starch on the backside and let dry, then mist from the front side and press.