Last Sunday we arrived at 5:15 for a 6:50 flight. We made it to the gate with 35 minutes to spare, but by 45 minutes before flight time they had changed the signs to "BOARDING", which was a startling thing, as they usually start boarding 30 minutes out.
There were a large number of standbys trying to use our flight to get part way back to Chicago, and they started giving away seats to them just as we walked up and got into the A line. (Those were seats for which no one had yet checked in online or at the airport.)