By the sounds of it, you want the action to happen on the first time a user logs in, but not on subsequent logins, is that right?
If so, you could look at using Group Policy and things like the RunOnce registry key.
Or you could make a "flag" that the logon script looks for to determine if it has run or not.
Would you need it to run once per day / week / month etc, or just the once?