Denna achieved her CGC when she was about 15 months old.
It was a fun class, and being able to tell people she's certified by the AKC as a Canine Good Citizen (which means I've also signed a contract to be a Good Dog Owner) is priceless!
It doesn't change BSL rules at, say, private RV parks we want to visit whose insurance doesn't allow "mastiffs"... but, that's their loss.
#2 and #10 are still hard for Denna.... she gets excited when strangers want to give her love and pets (and over-reacts at times), and she has become more and more of a mommas-dog as the years have progressed, which makes sitting with a nice stranger difficult if I'm out of sight - but she does manage when needed.