If he has a SW upgrade from last year then he can upgrade anytime in advance even though it is a V fare. If it is a new SW upgrade than he can upgrade one day before the flight. His chances of upgrading one day before the flight depend on what type of plane he is on. If he is on the 321 than he has great chances, but if he is on the 319 then it will be up in the air. If he is on the 319 he might want to get to the airport in time to standby on a flight with a 321.
SDFlyer