This is the way I do quilts when I bring the backing around to the front and hem. I use my ruler to slice off the corner making sure the edge of the ruler is 1/4" from the point/corner of the quilt top. I like a wide hem so I trim the backing 2" all the way around the quilt. When stitching the corner, I only stitch half and then back stitch. Then when I "pop" the corner out, it easily turns under for a 1 inch hem. My Mother-in-law taught this to me 10 plus years ago. Once you get the hang of it you will absolutely love it. Practice on scrap material first.