how can i tell how long someone has been offline?

I am waiting patiently for a nickname to become "free" so i can use it, however I have no idea how long it will take and am simply wondering if there is a way to tell how long its been since a player last logged in. I haven't been able to find this using google, the forums or this help center, hence I'm asking. This would be extremely useful as it would allow me to know when the nickname will become free and i wont have to check by attempting to use it every day.