Border Help using Y-seam
My Plan: I am making a wall hanging (28" by 28"). I want to finish it with two borders. The first border is only 1/2" finished, so I will add it to the top and bottom, then the sides. The second border is a striped material, and I would like to add it as a staggered border, 2" wide, where each side is (3/4 + 28 + 3/4 + 2 1/2) in length. The last seam would need a Y-seam to enclose the box.
What is this technique called? Does it matter which side I start on? Should it be added clockwise or counter-clockwise? Is my math for each border right? I'm looking for a tutorial or instructions to reinforce that my plan is do-able.