
Most toy breeds don't leave home before they are 12 weeks & during the extra time do learn manners via their mother. My Rjj has never nipped or offered to growl etc, I got him at 13 weeks old & he was with his mum until the day before I got him-he's a Border Collie & they are usually quite nippy as puppies.
Cavaliers are incredibly quick on the uptake if corrected the right way & as they are people dogs, saying ouch & moving away teaches them that if they nip they get left, so not to nip is good. It will get better believe me, the growling is not aggression btw just dog noise that they make when they are enjoying themselves, my GSDs used to sound like they were killing each other when they were in full play mode.
Cavaliers as adults have soft mouths like other spaniels & gundog breeds so teaching them not to nip you is very important
The link is very good BTW