When you're done, put your old belt in your tool bag in the trunk of your car and make sure that you have the 19mm and 13mm sockets there just in case you have to change it on the road some day.
I had to change one in a parking lot. It was a quality belt too, with only 15K miles on it...
I actually keep a NEW belt in my trunk now. That way, if it ever happens again, I don't have to put my old, used belt on just to get home and then immediately change it again for a new belt. Also, the fact that I now have a new belt on hand gives me additional incentive to change it at the first sign of wear.