Before my cycle regulated, I was very irregular. We're talking 22 days one month, then 35, then 18, then 27, then 12. Back then, I wouldn't get a bfp at least until day 35 even if I had every pg symptom in the book from week 3 on. I've even had a bfn poas at day 30 but had a blood test done too just to be sure (I was puking and everything) and that came back negative as well. Two weeks later, I poas again because af hadn't shown yet but got the shock of a lifetime when it came back BFP! Even now that I'm on a regular 28 day cycle, I still can't get a bfp until day 27 at the earliest.