Question: Delaying a task scheduled with cron

[paxw-panevo]

We have a custom periodic task (a subclass of django-celery-beat's PeriodicTask model) that's scheduled using CronSchedule. In our custom periodic task, we want to allow an optional delay to when the task is scheduled.

So if the cron schedule is every 20 minutes, with a delay of 30minutes then it should be scheduled to run

Without the delay: 00:00, 00:20, 00:40
With the delay: 00:30, 00:50, 01:10

How can I do this in django-celery-beat?