The FSS basically counts down from 7,000 (I think).
It will not sense your oil's age.
It is purely a countdown, dictated by your driving habits, towards the next oil change - 7,000 intervals.
Wait until your FSS says 7,000 miles overdue, and it's time for another oil change.
Then reset the FSS using the method described somewhere on this forum (use search - obviously!!!)