As I usually say, I'm no expert BUT...:)
Here in France in French ringsport we try to teach bark very early, although with our darlingsz it can take time:p ...It took leader 1 day (after almost 2 years of trying all sorts of ideas, one day I sat down in the living room and held his bowl just above his head and said Bark until he did and THEN he ate...it took him 3 hours:( )
With my little Blaze I tried something else. She's a barker anyway so every time she barked I said bark and praised her...she learned really fast and barks to go out, to open a door, to get a treat , to be fed, and to bite in ring sport when we do the seek and bark (my invention. I don't know the name in English. when she has to find the decoy in a blind....and then bark to let me know she's found him...
). She was really easy to teach, Leader still sounds like he's just clearing his throat, except in the ring!:D :D )
Hope this helps. By the way Blaze is 6 months old.
Leader