I love that you asked this! I KNEW I was pregnant within days of conception. I could feel it. I had all the symptoms, and many that I didn't realize we symptoms until I got them. After several failed pregnancy tests I gave up when I thought I felt my period coming. When it still didn't come a few days later, I took a test again and there was the slightest positive line.
They say you can test five days before your missed period, but more than likely you won't see results until after your missed period.