Hpt 5 days sooner?

Has anyone really gotten a positive test on the "5 days before your missed period?"
​The reason I ask is because I had a strong positive that faded after 30 seconds with some store brand hpt my roommate had, (I figured it was either a faulty test, or there may have not been enough hormones in my urine ) So, later that day I got the first response hpt that claims it can detect it five days sooner.. (This was three days before my period was due) And got a negative result. So naturally, I was confused when my period didn't make an appearance this morning. (I'm always regular, I have my periods down like clockwork.)