Window sill is going to be purely a novelty just so you know, unless your window sill receives like 18 hours of sunlight. You can start a plant in the window now because it is too cold outside but then you would have to transplant outside if you wanted a plant to grow to full maturity and be strong and healthy. It takes a lot of surplus energy to grow healthy strong buds and unless it gets more light then that it will not be able to do so.
You could look into advanced techniques to keep it small and flower it quickly, I just dont foresee a plant grown strictly on the window to come out the way you picture it. Prove me wrong though!