You can find Rules API examples from GitHub - SmartThingsDevelopers/Sample-RulesAPI: Rules are a versatile tool, enabling you to automate the Devices and services that connect to the SmartThings Platform. When possible, Rules execute locally on a Hub.
This example in GitHub is for starting rule at given time each day.
EveryAction also supports a specific option as well. In this case we can create a rule where we turn on a light at a given time each day. The reference field allows for a number of options: (Now , Sunrise , Noon , Sunset , Midnight ). You can then use the offset to fine tune the time to execute at an exact time every day.
It’s also possible to add and modify Rules API rules using Web tool.