NASCAR Racing: Name on Trophy, winners circle, checkered flag

Question
By the time a driver gets to the winners circle his name is on the trophy. How do they do that? Do they make or engrave it when the checkered flag waves? Do they have them made up ahead of time and attach the appropriate one at the end of the race?

Answer
I have never seen the drivers name on the trophy right after the race, but then, in my years in NASCAR I never made it to Winners Circle. I would imagine if they manage to get the name on the trophy it must be a stick on plaque that will be permanently engaved later. Sorry, I just don't a better answer.