If you go to McKenna Ryan's website, she has a section on Helps and How-To's that talks about how she makes her quilts. She does not sew around the edges first but instead, stitches around the edge of each piece after sandwiching it so that it acts as the quilting also. If it's a big quilt with numerous blocks involved, she starts in the middle block, sews/quilts around all the edges, then stitches in the ditch around that block before moving on to the next one. After all the blocks are finished, then she goes back to do some background stitching/quilting. By then the quilt is completely stabilized. Reading her technique might help you but of course, you can always do it however works best for you. I did it her way because I did not want to stitch around each piece twice, once before sandwiching and once after.