"Come November you're mine" ???

If you go by the Rocky timeline then the first Rocky/Apollo fight took place on January 1, 1976. The rematch then took place in November of 76. Some boxers who are considered gym rats train even when no fights are lined up. But in general a boxer starts serious training about 6-8 weeks before a fight.

Their first fight took place January 1. In a later scene, Tony/Duke says "He's been doing nothing for six months" when trying to talk Apollo out of fighting Rocky. So it is at very least June before Apollo starts his humiliation campaign, and we're not sure how long that lasted before Rocky agreed to fight him.

The Heavyweight champion would usually fight once a year. The same applies to most of the other weight classes. Champions usually defend their title once a year. Some twice.

In terms of actual training for a specific fight then you would start training at least 12 weeks before the fight. That would be fight specific training, conditioning, tactics, and diet control. However a professional fighter would always be in great condition the rest of the year round. In most cases anyway, but funnily enough the heavyweight division produced the majority of the exceptions to that rule. There were a lot of out of shape heavyweights walking into the ring in the 80's.

In Rocky's case yes he would have trained outright for a year, because he wasn't a professional at an elite level fighting regular before his first fight with Apollo. He would have needed the 12 month conditioning phase.

To draw comparison to a real heavyweight fight and situation, when Frank Bruno first fought Mike Tyson he trained for a year, and confirmed this after the fight. He was asked if he thought he could have done anymore after wobbling Tyson with a big punch in round five. That's when he mentioned how much he put into the fight and said he couldn't physically do anymore.

In the lower weight divisions world champions have been guilty of overtraining for a fight and have lost their title as a result. Barry Mcguigan is an example.

The Caretaker

rocky knocked his wife up and kid was born before the fight I think so use that as your timeline. 9 months at least went by.

Rocky retired after the first fight and had to be goaded into the rematch by Apollo. Adrian was super prego when the contracts were signed, so they only trained for maybe 6-8 weeks standard for a title bout.

It's said that rocky has been doing nothing for 6 months, Adrian gives birth a month early so around September and the press conference was before this so possibly August. When apollo says come November you're mine! Meaning its around 12 weeks before the fight. Hope that clears it up