some directions say to stop 1/4 inch from corner, pivot your quilt to do the next side. then to put your needle into the binding at exactly 1/4 spot where you stopped before. it's difficult to do since you folded your binding.
so i do my pivot and start sewing just above the fold-which is "off" the quilt.
and another quilter is right, the fold can be just a tad below the raw edge of your quilt, just so you can see it peeking out. not much. this helps you catch that corner.
that way your stitches sew that corner well and when you fold your binding toward the back, you don't have any unsewn area peeking out at you. most frustrating to have to go back and hand sew those.
http://quilting.about.com/od/binding..._binding_2.htm
see #3 is what i mean, they say to start right where you left off? i start above that-off the quilt, then onto it.