The binding should be full and an even width on the top and bottom of the quilt. Using a 2-1/2" binding and the 1/4" foot leaves a 1/4" binding on the front and a 3/8" binding on the back.
I have found that if I use the standard sewing foot, instead of the 1/4" foot, then when I wrap the binding over, it is full and is the same on both the top and bottom. This works with my standard foot and has worked for many of my students. Not all standard feet are the same so, if you try this, you may need to make a minor adjustment.