I raise and train labs (amateur not pro). I found John & Amy Dahl's 10 Minute Retriever to be an outstanding foundation through about the first 6 months, after that I use Evan Graham's Smartwork and Smart Fetch Program through intermediate to finished. When I begin formal OB at 12-16 weeks I do two 10 minute sessions a day that gradually lengthen to maybe 20 minutes absolute tops at about 12 months, when a pup's ability to learn and attention span take off. Takes me roughly 16-24 months to train a dog from 7 weeks old to Finished. my finished lab has rock solid OB, is steady to wing & shot, delivers to hand, will do multiple marks out to several hundred yards, handles on land & in water (blind retrieves), hunts upland, and hunts waterfowl out of boats & field blind. Just for the fun of it I teach them to blood trail, article search, find and retrieve lost arrows, and find sheds. They love these little games which are simply extensions of their hunting training.
The best advice I got when I was learning training under a pro about 20 years ago is to let pups be pups. Let them explore, fiddle in shallow water, learn to potty outdoors, learn what they can chew & what they can't, just learn their world. Around 9-10 weeks a couple times a day I do puppy bumpers (mini-paint rollers work well for this) in a hallway with no open doors. I hold the pup then show them & tease them a bit with the puppy bumper, then toss it a couple feet in front. The pup will want almost from the start run and grab it but their inclination is to keep it and will look for a place to take it. Call it back, when it comes, praise it up, gently take the bumper, and repeat. Do no more than 2 tosses twice a day, then put the bumper up. The pup never gets to use the bumper as a toy, and you always want to stop with it wanting one more try. You will be amazed how quickly your lab pup puts it together and starts bringing it back for another throw. As it gets older and you take this game outside, use a light check cord on it's collar to "reel" him/her in as it will try to run away with the bumper (remember, it's instinct is to keep what it catches, not give it to you).
For waterfowl gundog training help, there is no better place than the Gundog Forum on The Duck Hunter's Refuge. Decades and decades of experience there, and they are willing to share...