I begin by quickly sketching out on an 8.5 x 11" piece of typing paper where I want the panels and a rough idea of what I plan on drawing in each one. Typically I spend anywhere from five to fifteen minutes on these, depending on what I'm specifically trying to draw on the page and how much might be involved. I try to work out the kinks, trying to figure out how to draw things I might not have ever drawn before. Obviously quality isn't the goal here, so it's very rough. It's meant to give me an idea of the direction I want to go, so I don't run into problems on the final page. I might not even draw the same thing on the final page that I planned on the layout page (depending on if it feels right or works out the way I planned), but 99% of the time I will.