Where does Asch the Bloody fit in the timeline of Tales of the Abyss?


I got the limited edition of the first volume of the anime, which came with
"Asch the Bloody" manga. I figure it's mainly about Ache, but I'm wondering
when the story took place relative to the main series. Did it take place
during the 6 years he was with Van, or did it occur in the same period as in
the anime/game?

