i have done the national on brembos and i thought i would destroy my pads as well so i changed them afterwards and they were fine 3/4 left all round, your only out there for 15 minutes or so, depends how much tread is on the pads and how late you want to brake
Definitely worth warming them up first, dont be tempted to tear off with the other people that are under some odd delusion they dont need to warm anything up
also when you see the flag make sure your last lap is a cool down, dont hoon it and then stop, otherwise you will cook the pads