I know it's generally assumed (Well, at least by the DC comics and some novels which are non-canon) that the crew did a 'seven year mission' or something like that after the Nimbus III inciddent, and of course Sulu at some point got promoted to Captain, presumabely three years after TFF.
However, I've read that VI originally had the crew already retired and recalled to Starfleet for one final mission. There's also sort of implied in some of the dialogue I think (McCoy doesn't seem to know that Sulu had been promoted, when you think he would've noticed his absence from the crew) Also the crew hasn't met Valeris, but presumabely they would have had somebody fill in for Sulu (and yes, I know that the DC comics placed Saavik as Sulu's replacement for a while).
However, I've read that VI originally had the crew already retired and recalled to Starfleet for one final mission. There's also sort of implied in some of the dialogue I think (McCoy doesn't seem to know that Sulu had been promoted, when you think he would've noticed his absence from the crew) Also the crew hasn't met Valeris, but presumabely they would have had somebody fill in for Sulu (and yes, I know that the DC comics placed Saavik as Sulu's replacement for a while).