I am about 7-8 DPO (don't chart, just use OPK and monitor CM), and I have had some off and on dull cramping today and yesterday. So, it'd have started at 6-7 DPO for me. It feels like AF cramps, but a lot lighter and duller. I have not had any bleeding or spotting though. I don't think I did when I was pg w/DS either. He was a total surprise though and I was 6 weeks along by the time I realized it, so I don't have any recollection of my first pg experience.