I almost always use basting spray. And recently I have started the sandwich with the batting. I lay that flat - tape it down if the quilt is bigger than baby sized. Then I smooth the backing fabric onto the sprayed batting, making sure it is all totally flat and wrinkle free. I let that sit for a while, and hour or more, and then - usually with the help of a friend I turn the quilt over so the backing is now on the table. I spray the top of the batting and then carefully place the quilt top on it. This works so much better for me. When I would start with the backing on the table, no matter how much I ironed, taped, smoothed, etc, I wound up with a lot of wrinkles on the back.