Seating on Southwest Airlines?

While it is certainly possible to be in the A group by checking in 24 hours before the flight, it's not really likely and I wouldn't count on it. Between Southwest's frequent flyers and those willing to pay the extra $10 for early bird seating, the A group is usually full or close to it when the online checkin window opens. You may still get in A but it's more likely that you will be in B.