If you identify what type of limit you have and the nature of the specific limitation as is regards your story, it’s relatively simple. Once a threshold is met with the Limit, a Driver naturally follows, otherwise you’re covering territory that you’ve already exhausted. The limit can be used as a trigger for a Story Driver. It need not be so causally connected, but the driver often happens in loose proximity to a limit indicator.
TIMELOCKS:
Timelocks primarily come in two flavors: Deadlines and fixed amounts of time. The key for timelocks is that you must explicitly indicate the temporal movement toward the limit. If it’s a deadline, such as a date, then you need to reveal dates closing in on the final date. If it’s an amount of time, such as 24 hours, then you need to reveal time indicators (e.g. clocks, timers, countdowns, etc.) counting down toward the limit.
It seems that there is a storytelling convention where the amount of story time (not screen time or pages) between the timelock indicators tend NOT to be linear, but more like geometric series, where the earlier limit indicators span far greater amounts of time than those nearing the limit.
OPTIONLOCKS
Optionlocks tend to come in two different flavors as well: limited options and limited space (think ‘road trips’ from A to E through B, C and D), which is why we originally called them Spacelocks (glad we changed THAT label before we released v1.0!).
Like all limits, they can be highly specific or more generalized. From a writing perspective, you should at least be aware of what the options are so that they are in your story and may be identified by the audience in retrospect.
For example, one story limit may be as specific as having three wishes. Once the last wish is used, the story is primed for the final conflict. Another story may require a number of conditions to be met that may not be clearly defined so long as once one has been met or exhausted, the story moves on to another of the limited options.
The limited options in soft-edged optionlocks are frequently more obvious after the fact than during the story. Sure, there were only a limited number of ways the Empire could locate the Rebel base to blow it up, but we did not know what those options were until they were presented to us as an audience: scout the old Rebel hangouts, convince Princess Leia to give up the location, track the Millennium Falcon to the Rebel base, bring the Death Star to Rebel base and…climax! This is one way to look at the optionlock in Star Wars. Another would be tied to the Death Star plans: Get the data to Obi-wan Kenobi on Tattooine; get the plans to Alderaan; get the plans to the rebel base; figure out how to exploit the plans…climax!