Your question isn't really clear on what you're trying to accomplish. Are you trying to program the stepper so that it will spin the gobo wheel to the start position? For this you might use a limit switch, a proximity sensor or something similar.
If you're looking to spin the gobo wheel to a known location, you can store the stepper's current location into a variable using stepper->currentPosition(); and then at some point later, you can send the stepper back to that position with stepper->moveTo() or one of the other move strategies.