I use the June Tailor spray and never have any problems starting in the middle, the corner, the edge or wherever I want. If you have it spray basted and don't have any wrinkles, then the quilting will not cause any either irregardless of where you start. The trick is to get your backing smooth and wrinkle free, spray the backing and smooth out the batting. Do the same with the quilt top and you will have no wrinkles. I have never had to add pins, nor start in the middle with the FMQ. I think it is all just personal preference and sometimes is a habit to start in the middle (and a very hard one to break....LOL). It's your quilt, do what works best for you.