Hi everyone,
Thanks for the post and comments 
We’re currently working on a feature that will enable this requested feature. We’ve recently released a new type of workflow delay, a “Delay until event happens” action. To build on that feature, we’re currently working on adding additional functionality, that will allow you to delay a workflow until a task, created earlier in the workflow, has been completed. Stay tuned to this thread for updates!
Best,
Megan