With my first I knew I was pregnant when I saw I had implantation bleeding. My mom never heard of such this but it does happen
About a week after. This time I didn't take one until I was about a week late....but I already knew. The implantation bleeding was a dead give away for me. I had it when I got pregnant with my first but didn't know then what implantation was or that it was a thing...if I had I might have known sooner.
I never had implantation bleeding and not too many women have it. Usually post conception, you get a positive test around 14 days later. good luck