I tape my backing down, making sure it is taut, no ripples etc.t, then I lay my batting on, roll half the batting back, spray it then lay it back down on the backing. Pat it down and then do the same to the other half.
Lay your top on, making sure it's flat, then fold half back, spray the batting and lay the top back , again patting it down...do the same for the other half of the top. Large tops I get hubby to help me so that when we lay it on the sprayed batting we are keeping it taut so so no wrinkles form. :)
You don't need to spray a whole lot, just lightly spray over the area....lay out newspaper around to protect the area around your quilt from over spray.