There is a method for making continuous bias binding. I don't know where to find it on the computer but here is generally an explanation if you can find it. Search for Continuous Bias
You take the square. Cut it diagonally and then you sew two edges together and then into a loop but overlap the seam the width of your binding. Then mark the cutting lines. It comes out all sewed together.
Search for it. I am sure it is there.
If not this way, then I cut diagonally and then continue to cut the strips along the diagonal edge and sew them together.