after 5 generations on the dam side and 3 generations on the sires side...talking about best to the best of linebred and inbred dogs I gave a 10 week old pup to one of my brothers for a blood trailing dog...I gave him a pup that had a good winding and trailing nose...two years later he wants to get rid of him because he never did anything with him...I took him and put him in the bay pen and took to baying like a pro pen dog...took him to the woods and he was hunting as good as the other dogs...second time out he took a hog by himself for a couple miles and swam the brazos...Someone caught thdog on the other side and called me to go get him...but he was a hunting dog...when breeding it is best to look for nature ability and inclination...if you have to hunt a dog 2 or 3 times a week to make a hunting dog out of it then we can expect the same from the pups...
the above paragraph I copied from another thread where I posted it...so yes...a well bred dog does not need to be exposed as a pup for it to do the job once he is started...even at 2 years of age...but all the dogs in this dogs background that I mentioned had been tested and exposed to trailing and baying shoats a few times so that I would know who started when and how well they could work out tracks...I even tested them for how they took to water and who swam like a gator...meaning that all you see is a wake and no splash just the water moving and the dogs head moving smoothly forward...I also noted if a 3 1/2-4 or 5 month old pup bolted the first time in the woods and went and made a big loop...all this was documented because I wanted early starters for hunting and breeding...early starters but those that did it naturally...we can call it training, conditioning or exposing the pups...the meaning is the same to me...but then the pup has to be hunting pretty good at 10 months old and one will always rise to the top and that one gets to breed...I also ran them and found out who had the heart to keep running and finish first...I let them run behind the truck and after a mile of hard running I let the lead dog beat me so that made me stop because that was the game...pass me up and I gave in...all this testing was only a game but it served a purpose for me and the pups...
loading pups and unloading pups and making trips here and there is all for a good reason...
the bay pen is nice but it shouldn't be over done...kind of like ice cream...a kid that has all he can eat too often and after a while he won't want any more...give him a little ice cream every now and then and he can't get enough...same principle with the pups in a bay pen...
staged hunts are good too...don't need many but a few...same thing with teaching them to bark when rigging the pups...stage the hog upwind and make sure you know exactly where the wind is carrying the hog scent across the road...when you get to that point encourage the dogs to bark and once they do drop the tailgate and let them go bay a hog...when using the bay pen the pups must know to respect the hog or the pup could get killed the first time in the woods...
I don't do much of this anymore but still know how...

it doesn't take days or weeks of doing all this just a few times here and there and it is all that is needed...
Or like some others have said on here...turn the pup in to the bay or turn the pup out in heavy and fresh hog sign...
all kinds of ways to start the pups but my vote is to work them when you can...just don't over do it...