How does the cue-ball-control clock system work?
Here’s a good clock system handout (and diagram below) illustrating the basics. Buddy Hall does a good job of explaining and demonstrating the clock system in the following video: Buddy Hall’s clock system.
This system is a good reference for known shots like this. For other shots at different angles and distances to the rails, things will vary some. Cloth and cushion conditions also affect how well the system applies.