Right, I am putting it forward, because I think it's a novel idea! However my concern is that there would be no actual certainty for Dates. Maybe some form of Quarterly "Upcoming Events"?? As you know there have been recent changes to events where you will get a countdown, or around 48hrs notice for Fellowship Adventures, but we do understand how keen Players are to have advance notice of other things such as the Artifact turnaround.
In the meantime, keep an eye out for our Update Announcements from @anonglitch
concerning Artifact Turnarounds. Anyway i'll throw the idea forward guys. As always I can never give an immediate answer on these so please bare with me