I watched the tutorial and I do it about the same. The only caution I would say is to make sure to do one whole side with rulers before cutting anything. You can get a perfect square but have the design off if you don't make sure that the square you are cutting is centered. I work on the floor with my knee pads on. I lay my quilt flat and put a square in each corner on one side and connect the 2 squares with my other long rulers. This allows me to make sure that by squaring up one side, I still have the top and bottom edge lined up so that I don't cut off any points when I do the next side. I also use my chalk pencil to mark the cutting line all around the quilt before cutting anything off. It is much easier to hide the chalk line in the binding if you have goofed. At this point I measure with a tape to check if the quilt is the same size top to bottom and left to right. If everything looks good I then proceed to cut with my rotary cutter and ruler and pushing my rotary mat along under the quilt as I go.