Wirelessly posted (BlackBerry: BlackBerry8530/5.0.0.601 Profile/MIDP-2.1 Configuration/CLDC-1.1 VendorID/417)

Here are the details from aa.com:

"First checked bag free

For benefit to apply, the CitiŽ./.AAdvantageŽ account must be open 7 days prior to air travel AND, reservation must include the primary cardmember's American.Airlines.AAdvantageŽ number 7 days prior to air travel."

So it appears that it doesn't matter when the tickets are purchased, but the credit card must have been opened at least seven days prior to travel, and the AAdvantage number had to have been in the reservation at least seven days prior to travel.