I cut my bindings 2 1/2 inches, then fold and iron so I am sewing a binding strip onto the edge of the project that is 1 1/4 inches wide. Sew your binding strip to the front side as you would normally do. Fold over and press in place, especially the corners. I use hair clips to keep mine in the perfect place till I sew it.
Then put your binding foot on the machine and adjust to the width of the binding so that the needle falls in the inside "ditch".