If I have learned nothing else from training retrievers (not pro) over the past 35 yrs, its that not all dogs train the same.
You can say "generally", but never say never. Many pros espouse e-collars prior to force fetch, Many Force fetch as soon as the pups adult teeth are in, often before 6 months.
I have been witness to several pups who were mentally ready for the e-collar in the 4 month time frame. Can't say I've noted any ready in the 3rd month though.
If the trainer is pissed off and yelling at the pup, and the pup is being even nicked multiple times, there IS something wrong. Proper training has not proceeded the collar reinforcement.
Also keep in mind that no matter how well you try to simulate real hunting in your training scenarios, real hunting is a different animal, dogs sense it and can react differently than in training. A point of great frustration for many hunter/trainers. Used to see the same thing happen at tests quite often. If you are ready for it and have preplanned what to do in the event pup does not behave properly, you and pup will both be better off.
