I am now dealing with this and I was confused as well.
I met the $2000 spending requirement during my last cycle, which was 11/19-12/18. The "Rewards Dollars" for the $2000+ spent showed up in my Rewards History on the Chase site on 12/19, however I still haven't received the credits in my AirTran account. Called Chase today and they informed me that the credits would post on 1/18/14, i.e., the end of the next cycle. The rep told me that was standard practice and there is no way to accelerate it. She also restated the 6-8 week timeline -- I guess they mean it could be 6-8 weeks from the time the spending takes place? I crossed the spending threshold on 12/10/13 so that will be almost 6 weeks for me between spending the money and receiving the credits.
I'm hoping to use these for a trip to Punta Cana in February so this is going to be cutting it close.