Flight loads look pretty good for nonreving. It is usually pretty easy to nonrev out of and into Charlotte. Depending on the hire date of the person who gave you the buddy pass, you should probably be able to get on any of the flights out of CLT. The first to ATL leaves at 6AM. Then you would take flight 1480 to SAT. It is always better to get on the earliest flight possible. All you have to do to check in is go over to the Delta Direct phones near the Delta counter and tell them you are on a buddy pass. It is recommended to not check any bags in case you have to change your route. You should be OK for your flight back to CLT, also. Have fun!