IMO Force Fetch/Collar Conditioning is essential, I won't have a dog that isn't FF/CC. It turns retrieving from a fun game the dog does when & as long as it feels like it, into a fun task to be done perfectly on command. As an aside, every dog I sent off for FF/CC came back with even more enthusiasm to train, if that's possible with labs.
Without FF/CC, you don't have a tool to correct a refused retrieve and sooner or later, every dogs refuses. In addition to being able to correct a refusal, collar conditioning gives you a method to communicate with & guide your dog from a distance. For example, I use the page feature as sort of a tap on the shoulder to tell my dogs when they are hunting too far out, a reminder that they need to pay attention to me as well as finding birds.
I agree that you should pay a pro to FF/CC your dog if you've never done it. IMO it does a dog good to undergo training from another handler who isn't emotionally attached to it. There is no way to put completion of FF/CC into a hard time frame. I've had dogs that breezed through in 6 weeks, and one that took 4 months that we nearly gave up on & washed out. That dog, who got through by the skin of her teeth, developed into one of my best ever at three hand casting. I would say on average, it has taken 8-9 weeks for my dogs to complete...