There are a number of properties on the global $user object https://api.drupal.org/api/drupal/developer%21globals.php/global/user/7
But I can't figure out how to see if a logged in user has ever previously logged in, or if this is his/her first session. When logged in, the $user->access, $user->login, $user->timestamp values all seem to point of the current session.
I can set a cookie and check for that cookie myself. But I suspect I'm just missing something Drupal already has ?