With my first two pregnancies, I had a sharp cramping pain that felt like ovulation but lasted a lot longer and was after ovulation. I had a positive test before my period was due both times. Other than that, no symptoms until 6 weeks or so.
With my third pregnancy, I found out after I was irrationally angry at the world for more than two weeks. I had implantation bleeding that was the equivalent of a period, so I didn't think about pregnancy. I was around 6 weeks when I found out.