I would like to make some 6 1/2" pinwheel blocks. I want to use the 2 square method using 1/4" seam around the 4 sides then cut diagonally to make 4 half square triangles. My question is how big do I have to cut the 2 squares? Hope I have made this clear but am sorry if I have not. This is the first time posting and I have no doubt there is someone out there who can help me. Thank you in advance.