For those who have gotten a BFP

I see a lot of posts about getting faint lines on HPTs that build to darker. Has anyone ever gotten nothing, no faint line or nothing, right before AF and then gotten a positive a day or two later. AF is due Saturday or Sunday and this morning I got a BFN and there was no hint of a line. Based on a lot of these posts, it seems I should have gotten a faint line today if I was pg.