Hand piecing is the best way to avoid puckers however, if you want to do it on the machine make a dot with a washable marker 1/4" in from each point. Sew them together just like any other Y seam, going from dot to dot. Time consuming, pain in rear but you'll like it when it's done.
Make sure that they're all the exact same size. If they aren't there's no way in the world to get them to go together evenly.