Originally Posted by
Often1
No, there is not.
If this is domestic, you can do it as late as the gate (although you do need to be at the gate a bit early). If it is international, you can do it as late as the ticketing deadline. But, given potential glitches with all manual processes, I would not push that.
You should do it at the ticket counter or machine. Infant needs a BP so shouldn't get thru TSA without one.