Track One Time Login
I never found a solution for that. I did it always the following way:


Install the rules module (if you did not work with Drupal's hooks yet - otherwise you could use these hooks for that)
Then give an user a role like "unconfirmed" as soon as a new user account is created by one rule
Then define another rule: triggering event is "user logged in", check, if the user has the role "unconfirmed" and if so -> action "Take role away" (do not know now what the action is called in English).