You can designate a pile of papers or the cage, or whatever is acceptable to you. Then he was praised, and taken off the perch. Sammy had perfected his bombing within three days. We rarely have accidents. You can choose whatever key word you like best, as long as it's not too common, which may confuse the bird if it hears its cue in normal conversations.
Some birds potty train themselves.
Some, unfortunately, do this using their water bowls and thus make poop soup. Apparently Quaker Parakeets are known for this. For a chronic soup maker, you may want to get a water bottle, like the kind used for hamsters. Birds that bite for the sake of champing might be better off as a breeder. Birds go through a nippy stage when they hit puberty.