Too early for PT?

Hi po! We're trying to conceive and i'm supposed to get my period last Oct 7. I had my PT today and it gave a negative result. Regular po ang period ko. May naka experience po ba dito na negative ng pt after being delayed for 3-5 days but still came out positive a week later? Masyado po ba early ang pagtake ko ng PT if i'm just 4 days delayed? #pregnancy