How to determine when it is safe to drop block storage volume/boot volume

Summary:

Have lots of unattached oci block storage and boot volumes that I need to delete. Trying to figure out a way to determine when this is safe to do so.

oci compute bv volume list shows me volumes

oci compute volume-attachment list shows me volume attachments

combining these I can determine what is attached/detached now.

I can get creation dates/times for the volume and the attachment. I would like to determine how long it is since a volume (or boot volume) was attached to an instance.

Reasons it might not be safe to delete a volume:

1. It has only just been detached, this was an accident and it will be reattached soon