Do you use any reference at this stage?
Normally, yes, since it saves me a lot of frustration and wasted time. This drawing, however, just came to me on the spot, and I put the sketch down on the canvas pretty quick. I might use references for some poses later on.
EDIT: One more thing: I sometimes find that when I rely too heavily on references for poses/anatomy, my figures become a bit stiff. Dunno if this is a problem for anyone else though.