In these cases, online bookings must be made at least 48 hours before the flight departure time. (flytap.com)
It seems you can call and start the award booking process and wait to finalize the transaction until days before flight date, if that's how you roll. (viewfromthewing.boardingarea.com)
I was able to get some food in my belly, work for a bit and then relax before my flight back to the states. (travelcodex.com)