I am so confused, and Delta is not able to explain this to me; maybe someone here can:

I got a RUC, and I am flying a LAX -> JFK route. Currently, I have a Main Ticket:
- To have the best shot at D1, do I need to use my RUC to put myself in PS and get upgraded to D1 upon availability 24 hours before departure?
- Or it doesn't matter, and I will still be on a D1 upgrade list 24 hours before departure based on status (Diamond)?