I'd do it a little different than toverly - I'd sew A 1, 2, 3, and 4 together as one unit, A 6, 8, 9, and 10 as another unit, A 7, 11,12, and 13 as a third unit. Then assemble those 3 units and the center triangle (5) together. That way the only sections that you really have to worry about matching up are the 3 main seams at the corner of triangle 5.
I'd also starch the snot out of all fabrics before cutting anything.