Timer Cycle and Durations

Very New to Flowable.
We have to create a DNS A Record , and the time window is 8PM to 3 AM for the API that creates the record. Outside of the time window, the requests has to be kept in a queue/DB. What should be the timer cycle and duration. I tried ‘R/2019-06-20T20:00:00’ for cycle and ‘RT7H’ for duration. I’m getting FlowableException: Failed to parse cron expression.

For duration, flowable use ISO 8601 Please see link.


RT7H is not ISO compliant, here R is invalid, it should be P.