I am starting production on my short little VN in march, and I was wondering since I did a rough draft prior to nanoreno, is it okay to use it or do i have to make a completely new game? All I have for it right now is 2 bare concept arts and a half finished script.

If you started outlining a project ahead of time, that's totally fine! However, all the assets you produce have to be within the month of the jam, so any actual dialogue, prose, or any words that would be in the final game have to be written in March.