when does the elf say goodbye

The Elf says goodbye to you when you say goodbye to the Elf. The Elf will only speak when you speak first, and the Elf will only leave when you tell the Elf to leave. The Elf is always ready to listen, and the Elf is always ready to follow your commands. So the Elf's goodbye is up to you. You can tell the Elf goodbye anytime you like, and the Elf will obey.