I think we're all wondering how the time frames line up for Percy Jackson and the Olympians and The Kane Chronicles. So here's what I think:

The Red Pyramid:

Happened the same winter as The Titan's Curse

The Throne of Fire:

Happened the spring before The Battle of the Labyrinth

The Serpent's Shadow:

Happened the fall after The Battle of the Labyrinth

The Son of Sobek:

Happened the summer of The Last Olympian, before the Battle of Manhatten.