What is the best way to monitor usage of concurrently used seats?

We have purchased a package of concurrent seats for the institution, but I am trying to understand the best way to monitor how many are being used concurrently. We will eventually have many users who will be scheduling their own meetings, so there is no good way for me to make sure that too many meetings will not happen simultaneously. Is there any kind of notification system to let me know when we reach a certain threshold of users? We got 200 seats to start with, but I am trying to monitor to understand if we will need more. I would ideally like to receive an email when 100 or 150 seats are used at a given time. Also, is there a way to manually monitor from within the admin interface? How are other institutions monitoring concurrent usage?

Thanks for any thoughts/comments!