Upgrade space on the JFK-SFO and JFK-LAX nonstop flights is not opened in advance. It's X0 through the end of the schedule, so everyone requesting an upgrade is on the battlefield. Unless something changes, if you want a chance at an advance confirmed complimentary upgrade, you'll have to choose a different route.
Though I'm sure that's sometimes true, I've definitely been upgraded at the 5 day window for JFK-SFO and SFO-JFK (this was in December).