I am a little on the hardcore side.
I like to see natural ability with pups...I like to see a strike dog pup winding and trailing tidbits at 2-3 months old and rolling out by 4 months old. It don't matter if they know what they are doing but it just tells me it is in them to be a good dog.
Same thing with a catch dog...I want to see them lock on a shoat at 3 or 4 months old. This is natural ability and I am perfectly happy putting the pup up after that until 10-12 months of age because I know they will do it when the time comes.
I like my dogs this way because I have a small yard so need the dogs to be good enough for breeding as well as for hunting because can't keep to many.
Don't always get my pups that way but that is the goal...and that is what makes me happy.
With your pup...someone mentioned that you should tie your pup outside the bay pen and let some bay dogs bay the hog, this is good advice, especially if you tie him in the area where the pup can be fairly close and see the action. Also it would help to tie a yound bay dog close to the pit pup but not so close to where they are baying each other or where they can fight one another. This will encourage him to focus on the pig by watching the other pup bay.
Once he fires up and wants in you can let him in...
You can not force the pup to catch. you can only encourage him to do so by setting him up for success.