I would say notify the UC’s only after your deficient grade is CONFIRMED, and by that I mean that the final grades are posted on your transcript. Meanwhile, try your best to bring that grade up as much as you can. Maybe keep screenshots of the percentage if it is towards the higher side, (65 up since it is still higher than a 60, which is usually assumed to be when a school sees a D). Also, explain the grade AFTER it is posted, and say what you plan to do to make up for it and WHEN. Make sure you have an actual plan and not just like “hey so I’ll make up for this but I don’t know where or when or how.” Sound like you have yourself together to the school, and they might be more understanding.