It’s not a publicly promoted, it was announced on Flyertalk: you have to register and then all stays in April will earn 1000 bonus points.
No need to rebook any existing stays, reservations you already have will qualify for the bonus. And in my experience, hotels sometimes even code award and cash and points stays as qualifying, so even if you only have an award stay planned it’s still worth registering ‘just in case’ it shows up as a qualifying stay.
