Bonnie suggests marking the sewing line for the corner squares.........
This way when the fabric is folded back over the corner it will completely cover the bottom square.
If you sew directly on the line you may find that when you press the fabric up it may not quite cover the base. To some extent it depends on the thickness of the thread used, a heavier thread takes up more space and it may be just enough to leave your corner triangle a teeny bit short.
I thought this was a very handy tip that I will certainly remember, it worked well for me whereas in times past I have found I have come up a wee bit short.
So, now I am all caught up with Easy Street and I can go into Christmas with a clear conscience!