The biting and nipping, even the rudeness/pushiness - standing in the way, sounds like typical behavior for puppy who is on his way to becoming (is not yet) an adult dog. As young dog with little self control he gets excited when he is greeting or gets a little amped up/ rough when trying to play, when it happens take a moment to consider what you could get him to do that would engage his brain and is incompatible with that behavior - perhaps cue a sit (sit to greet) or a down, even a behavior such as 'touch' your hand with his nose, or chase a tossed toy - and then reward him with a food reward (while he is learning the new, acceptable behavior) and give him the attention he is seeking.
Take a moment to consider that leashing him and leading him off to a corner to be by himself, is (in his eyes) a negative consequence for being leashed, the 'isolation' happens far too long after the biting/nipping for him to be able to associate it with that unwanted behavior.
It sounds like he may be starting to associate being leashed with negative consequence (isolation) hence the warning growl that he displayed towards your wife.
Dogs associate what happened next with what happened immediately prior to the positive or negative consequence, he cannot 'reason' /back track in time and figure out that being isolated is because of the rough play behavior that happened before being leashed and led off into the corner. The time out may give him the time he needs to calm himself, so that he doesn't immediately go back to the rough play, but he still won't understand why he ended up there in the first place.
While I can understand not having a lot of time to work with him, life is busy, but any time you can find now to invest in helping him now will pay off long run. Consider that he does need help to burn some of his puppy mental and physical energy. Perhaps taking some time each day reinforcing the skills he already has, doesn't have to be structured training sessions, a few minutes here and there works well too, brain games, 'settle', perhaps teach him some new skills that can help him to learn some self-control - leave it/ take it, wait/stay, go to a mat/bed and 'settle' there until released.
Take a moment to consider that leashing him and leading him off to a corner to be by himself, is (in his eyes) a negative consequence for being leashed, the 'isolation' happens far too long after the biting/nipping for him to be able to associate it with that unwanted behavior.
It sounds like he may be starting to associate being leashed with negative consequence (isolation) hence the warning growl that he displayed towards your wife.
Dogs associate what happened next with what happened immediately prior to the positive or negative consequence, he cannot 'reason' /back track in time and figure out that being isolated is because of the rough play behavior that happened before being leashed and led off into the corner. The time out may give him the time he needs to calm himself, so that he doesn't immediately go back to the rough play, but he still won't understand why he ended up there in the first place.
While I can understand not having a lot of time to work with him, life is busy, but any time you can find now to invest in helping him now will pay off long run. Consider that he does need help to burn some of his puppy mental and physical energy. Perhaps taking some time each day reinforcing the skills he already has, doesn't have to be structured training sessions, a few minutes here and there works well too, brain games, 'settle', perhaps teach him some new skills that can help him to learn some self-control - leave it/ take it, wait/stay, go to a mat/bed and 'settle' there until released.
