I LOVE Elmer's School Glue basting!!! For basting the sandwich, I just let it air dry. I lay down the batting (I like Warm & White), smooth it out and then drizzle about a third with the Elmer's School Glue. Then I center my top over the batting, patting down the glued section. After everything is smooth and patted, I fold back the top to where the glue ended, then glue another third. After smoothing and patting down the top again, I fold it back to expose the unglued third and repeat the process. After a few hours, I go back, flip the top/batting over, and glue the backing in the same way. I let the whole thing dry overnight, then either go ahead and quilt it or set it aside until I'm ready to sew.
When I use the Elmer's for the binding, I do use the iron for faster drying.