Starch then cut.
Starching will add body to the fabric and make it 'crisper' to cut which leaves a cleaner edge. It will also make the fabric flat, smooth, and somewhat stiff which will aid when cutting by keeping the fabric straighter and flatter.
Also, when you starch and iron, the fabric will distort a bit - so you want to do that before you cut it and sew it.
That said ... when I complete a block I will starch it again and press (not iron, but press - which means I just lay the iron down on top without moving the irong. To press a different section, I pick the iron up and lay it down again on the next section).