Yes, like LaH said, use an Always sensor with no pulse settings (neither [’’’] button is ticked). That will run the script once on scene initialization. It will also run on each new scene EDIT: that the camera is in.
“Add one” what? People do different things - for game initialization, I usually use an invisible cube floating in mid-air conspicuously somewhere. The camera could also initialize things as well - it’s up to you.