In my experience the spray works well only on very small projects. The last one I tried somehow ended up with the backing seriously off grain. It's messy and the spray gets all over your table and the floor.
You can't beat good old masking tape to secure the edges of the backing on the table. Then spread the batting and leave it overnight to relax so creases can be smoothed out. Then spread the quilt out on top of the batting and stroke it until it is straight and smooth. Secure the edges with tape. Then baste with needle and thread from the middle outward. Run a line of basting around the outside edge, remove the tape and quilt away!