personally i would start in the center and work my way out- meaning i would sew the center 4 together-forming the pinwheel- then frame it with the next round- sewing the 4 flying geese units, 2 with corner squares- attaching one on each side without the corners- then the 2 with the corners- then out to the next *round* until it was complete- doing it section by section. i've made this same square numerous times- and have always worked my way out- for me there is much more room for error trying to line up whole lines/rows when piecing the components brings it all together accurately.