Have ever been on an island vacation?
Yes, I have. I've already been on an island vacation. / No, I haven't. I haven't been on an island vacation yet.
Ask and answer: leave your home country
Have you ever left your home country? Yes, I have. / No, I haven't.
Have you ever been to London?
Yes, I have. I've already been there. / No, I haven't. I haven't been there yet.