Van's builder support (and many others online) recommended starting with the verticle stab before the horizontal. After looking at the plans and instructions, I agree.
Clecoed VS skin to frame for match drilling. Match drilled all holes #40. Debated whether to do alternate both sides of skin. Went ahead and clecoed the skin that was up, but couldn't get the other side down. Had to undo everything, start over, and alternate both sides.