The last "recipe" in the cookbook talks about project cycle time. I'm not sure if it's 100% what you're looking for, but it might give you some ideas!
Hi Kyna! Yes, I saw the Creative Production Cycle Time task report. Wondering if this would apply to a project report as well.
It should work, you would just need to pull in the project information instead of task information. So anywhere it says Task> Date Field you would want the equivalent Date Field on the project.