Join Date: Mar 2009
Location: NYC
Programs: AS MVPG, DL KM, Bee Six, Bonvoy Plat, Choice Plat, BW DS, Avis PC, Natl Exec, Greyhound Road Rewards
Posts: 19,973
Once check-in opens, you can only switch your seat through the modify check-in process. So you should have until Sunday at 11:30am and then you can change your seat until they start boarding I believe, or whenever they clear standby passengers. You can always ask to switch seats at the gate as well.
-J.