It's a nightmare just waiting for the car to switch off before you can lock it.
Mind to test your handbrake connection. With the timer running and the keys out of the ignition, press the brake pedal and let off the handbrake and the car should stall.
As an added precaution I also turn the steering wheel until the lock comes on, that way if anyone try's to steal it when the timer is running it will only move forwards.