Say you slipped off the top of Right Unconquerable at Stanage whilst soloing, and your mass was 85kg, it would take 1.8070158058105024 seconds to hit the floor and you'll travel at 17.708754896942924 m/s, according to The Splat Calculator that was created by a climber named Dave Anderson.
Enter the height of a fall and the Splat Calculator (website) will tell you how soon you'll hit the ground and how fast you'll be going upon impact.
Dougald MacDonald at his blog themountainworld.blogspot.com/ contemplates a bigger plunge from the top of The Nose of El Capitan.
"The distance from there to the pines below is about 850 meters. Plunge time = 13.17 seconds. It's actually going to be quite a lot longer than that, because Anderson's formula doesn't take into account the atmospheric drag that would slow an El Cap diver nearly to terminal velocity. Either way, it's plenty of time to contemplate what's about to happen."