I measure all of my quilts by laying a border through the middle and lightly smoothing it out to the other side/end mark it for cutoff. I then lay it on top of the other border strip and smoothly lay it out and cut the same size. I do the opposite side/end the same way. Mark center of quilt and border with pins and once or twice the same distance from the center pins, pinch at the pins as I sew easing in. Never had a wave or anything else. Works perfect for me. Never just one way to do anything. Do whatever works for you.