User blog comment:SayuriDarling/The Sword of Summer Official Discussion/@comment-5183385-20151007031418/@comment-24883778-20151007065306

My most solid theory is that it takes places in January 2014, which would make Annabeth in her twenties. Now why 2014? Here [Spoilers]:

- Winter month

- In the beginning Randolph wishes Magnus a happy birthday (January 13th)

- During their talk with Freya, she mentiones the 16th day of the month being Thursday, and the 22nd being Wednesday; January 2014, October 2014, and July 2015 all fits this category, but it has to be a winter month.

- Thor mentions shows like "Game of Thrones" (which first aired in 2011), and the League of Assassins from "Arrow" (aired 2012, the League appeared for the first time in an episode from November 2013).

Yeah, I think these evidence are pretty solid.