Four or five months of age is a good time to step up obedience training, though again it starts the moment the dog comes home with you. For retrievers, use dummy exercises to unleash and stylize abilities you’ll later use when hunting. For pointing dog breeds, including flushing dogs as well, moving through hunting cover is also a priority. Check current regulations to see if and when you can train this way in the off-season; states vary.
Retrieves from some distance are called “marks.” After you’ve taught the dog to sit and stay (this is crucial later in your blind), you can then toss a white dummy so that s/he can see it fall (much like a duck). These dummies are widely available. Use them, instilling fun and function in the retriever.
Control is crucial in training. Toss the dummy. Insist that your dog stay close. Release that retriever to cover the line from your location to the dummy drop spot. Repeat regularly as a form of play and practice; again make it fun for both of you.
I’ve hunted with sporting dogs for almost forty years now, and if I know one thing, the bond you build early when that canine is a pup will last a lifetime. Build the bond by spending as much time as possible with that dog, young or old, from the time you bring it home and the years after. This includes the off-season, and definitely when the season is open.
In the end, exposing your dog to obedience commands—fun and functional while retrieving, or simply moving through the off-season woods, marshes and fields—will make your waterfowl and upland bird hunting experience more fulfilling this coming hunting season.