User blog comment:Menara/The Son of Sobek: The official PJ and Kane Chronicles Crossover/@comment-122.164.234.74-20130211171738/@comment-5593616-20130211173541

We don't know yet, but since Carter said Percy looks around 17, and Percy's birthday is a month and a bit after Gaia's supposed to rise, I'm guessing (hopefully) after The Heroes of Olympus.