Just as a data point, I did an SDC (the first in years). I called in late afternoon to change from an am to a pm flight the next day. It was a little more than 24 hours before the PM flight. I'd been upgraded on the AM flight already and the agent kept my upgrade (The PM flight had PZ=2 before I called (PZ=0 after).
So ... 1k benefits were helpful for me this week.