As Prisim99 said, if your layers are held together well, you can start wherever you like. I use Elmer's School Glue to make the sandwich, and it handles like one piece of fabric. Thick fabric. I usually sew at least a basting stitch around the outside first because the glued pieces could separate with a lot of handling. Mostly I quilt down one edge at least a foot or two in, then turn the quilt at the corner and do that on side two, three and four. Then there is just a small center left to do. Haven't had trouble with puckers.