If you haven't seen Rob Davies' escape from a P-51 at Duxford after having the elevator cables severed by an errant Skyraider... I think the collision was about 900', over the side at 500' and the parachute is fully developed at about 250'.
I believe that he regularly rehearsed his bale out procedure and I have also heard that he also briefed other pilots at displays. You can see the canopy jettisoned almost immediately after the collision, he then tries to fly the aircraft before deciding to abandon.
https://youtu.be/xctYWSuwoYA