It depends on the design and what I intend to mark it with. If it's straight lines, I use painter's tape and do that after it's sandwiched. If it's a ponce, you do that after sandwiching and as you go. If it's a quilt pencil/marker of some kind that you need a hard surface under, I mark that as a top. IMPORTANT-If you are using any kind of quilt pencil, quilt marker, quilt chalk etc. do a test sample and then try to remove the lines before trying it on your quilt.