Question regarding an "ignition key activated 12 volt source"

I recently installed an electric choke and I need to know where the closest "ignition key activated 12 volt source" is as according to the instructions provided. Here's those instructions:

http://www.jegs.com/InstallationInstructions/300/350/350-1478.pdf

I've had not much trouble up until now and after searching through my car manual and google and I dont think I've found what they're looking for. I'm really excited about getting my choke put together and this is quiet a snag! Any help is appreciated,

~hobbly

I hooked my 12 volt choke wire to the power wire going to the wiper motor. What year is your Nova?