Back when I had an opportunity to get some questions asked by an exec involved with this promo this is exactly what they told me. It seems the timing in relation to your flights is flexible (although I wonder if there is some limit on the span of time between your flights and your stay), its just you can't get more than one bonus per one-way (unless they make a mistake). A lot of these kind of details are missing from Terms and Conditions, hence our struggle with these issues.