One thought on this...when joining the LAST of the binding to the FIRST of the binding... Begin sewing first binding about 6-8 inches from end....Stop sewing the end binding about 6-8 inches from end.
Measure the width of the binding, opened up. (That is the distance of one overlap when you lay the bindings on top of each other.) [[[[[pin this the first time to get your bearing on this, or make a mock-up on another 'quilt' to practice]]]]] Now, right angle the bindings to each other, as usual, pin, test your placement by refolding joined binding and lay on top of quilt edge. Open out, sew the two bindings together, and you have a perfect binding all the way around.