I would stay inside the a/c strapped in until it rotates and sinks....obviously the doors have gone by now and when the rotors stop turning..wave goodbye to the cab and calmly release your harness and mic tel lead and swim away from the rotor diameter before inflating your jacket.
The drills taught in the
RN dunker include waiting for all moving parts to stop before exiting the aircraft. In the training environment this means counting to ten seconds before releasing straps.