You missed my point entirely.

Your head start with window sill light would do more damage to the plant than good would do.

Your plant will climb, have 6" - 8" of internodal length, at least, and by the time spring came around you would have a physically mature plant that has already become a gumby plant of sticks and stems and maybe a few leaves.

Thats not really a head start....well not the kind I would think you would want.