Roughing the figures in nude is important because then I know where the knee will push against the robe. It is the cloth that will conform to the structure that lies underneath.
Here I begin massing in the figure being careful to remain loose and open to changes. My main goal at this stage is to get the gesture. I spend a lot of time measuring from all directions and use toothpicks to mark major points on the body such as top of knee, 7th C., shoulders, hips, nose, etc... This makes it easier to always be measuring from the same common locations and is useful later on when I begin massing in the clothing.