I do both. First I put my back onto my design board and pin it to board along the edges to keep it flat. I then spray it and place batting pinning it on edges as i go, then the top. I then decide how to quilt it and mark the edges of my area to quilt with my basting pins. I found this helps me keep track of where I am while quilting so I dont get so confused. I tried the pinning method before the spray and just found that all the pins got in the way.