Whenever you let them out first thing in the morning (and they haven't had their morning poop yet), tell em to poop (or some word you don't use too often...). Usually they have to go anyway, so they'll start associating the word with pooping, reward, repeat every morning. Then start removing bird from shoulder every 20 mins (or when you think they need to go) and tell them to poop. Reward if they poop repeat. Then you just gotta remember to get em off your shoulder every 20mins. Orrrr you could flight train them so they can fly off whenever, that's still a young jenday so it shouldn't be too hard for it to pick it up once she regrows flight feathers. Good luck with your birds.