How can I defer the execution of Celery tasks?

I think you are trying to avoid race condition of your own scripts, not asking for a method to delay a task run.

Then you can create a task, and in that task, call each of your task with .apply(), not .apply_async() or .delay(). So that these tasks run sequentially

eta/countdown options enable to delay the task execution:

https://docs.celeryq.dev/en/stable/userguide/calling.html#eta-and-countdown