Two methods work with the spray:
Roll up the batting and place it at one end of the wrong side of your backing which is stretched out on a table. Just do one light spray in front of the roll and move the batting forward over it, patting it down as you go. Repeat until the batting is completely glued and flat over the backing. Roll up your top and do the same process. If you are using polyester batting you will have to spray the cotton instead as the glue melts the polyester.
The second method is to fold your batting in half and do one half of the quilt and then the other in turn. Repeat with the top.
I live in a 'broom closet' and these methods work for me.