If your fabrics are directional, make sure you cut the slit for turning the circles in the correct side position. The 4 circles all need the slit to be in the center where you will be doing the fold over.
When you mark to match up the pairs to sew together, mark only on the L shape sides that go to the center. Since the other sides of the circle go to the outside and don't have a fold over, you don't want pencil marks out there.