Never.
Only ONCE with my 97 sentra did my fuel light come on. I actually ran out of gas one time, because I misjudged how much I had in my tank (Way back in the day, I used to get 360 miles to a full tank, now I get around 260-280), Not once did my fuel light come on. I'm curious about that...my dealer can't seem to find the problem. I just fill up now when I am at 1/4 of a tank. --> good rule of thumb, IMO.