I have read alot about this lately and with my first son. I also have some midwife friends.
Personally I knew I was pregnant right away and possitive after a few days. I felt a heaviness in my lower pelvic region, really sore breasts. Although right now I am breastfeeding and not sure if I am pregnant again. Some women get spotting when the egg emplants itself in the uterus. When you are ovulating most women get a clear to cloudy discharge that is almost like hmmm elastic bands it is stringy. That is when to get busy if you are trying
Other symptoms are being tired, really hungary or avoiding food like crazy. Food adversions, upset tummy.
Those come at about 4 weeks and on.
Hope those help otherwise you go to your doctor for a blood test they know right away or wait until the day your period is supposed to turn up and take a home pregnancy test.
Oh and this is silly but it worked for me listen to your dreams. I dreamt about a baby the night we got pregnant and it was true and for weeks afterwords and then we found out for sure.