Access the Flow Interview Start Time with a New System Variable
With the new $Flow.InterviewStartTime system
variable, you can use the start time of the flow interview in Decision elements, formula
resources, and elsewhere in the flow. For flows that are launched by Subflow elements,
$Flow.InterviewStartTime specifies when the initial master flow starts.
Where: This change applies to Lightning Experience and Salesforce Classic in Essentials, Professional, Enterprise, Performance, Unlimited, and Developer editions.