Depends on the game. I bought all the DLC minus Mothership Zeta for Fallout 3 because I could not wait to get my hands on it. I bought Fable 2 platinum hits because I rented it, loved it, and it had been out for a few years and the platinum hits was more bang for the buck.
For RPGs and FPS games, I buy the DLC a week or two after it is released.
As for sand box and all other types, I wait around for a bit until the DLC is in hardcopy then I buy the DLC standalone or as a GOTY edition or platinum hits.







