Great color. The composition is too symentrical for me. I want to reach out and move the King over in front of the pawn a bit more. I would more the rook and frosted pawn over toward the right edge and back.
I imagine you'll see a few comments about not meeting the challenge since this could be in any month, but i agree that that wouldn't stop it from being a calander shot... The slice off the pawn on the right bothers me a little, but I'll get over it :) Nicely done :)