Sorry if this has already been answered in this thread, but I couldn't find it (or decipher it).

I have a multi-leg itinerary upgraded one class of service using 25k miles. I want to fly standby on an earlier flight for my first leg (domestic). Am I out of luck and stuck in Y or will I be put in First if a seat is available? Where am I in the pecking order? I am Gold.

Thanks for any clarification