The day before i missed my period i had the fatigue and went to bed 2 hours early . the next day i found out why.
I am pretty sure it was almost immediately. I didn't take a test until week 7 though because I thought that I was getting the flu over and over (may husband was getting it) but my symptoms were a little different then his. looking back, I did have extra sensitive breasts the entire time and I was throwing up a lot. I hope that this helps.
My symptoms were how I knew that I am pregnant. at about 4 / 5 weeks I had sore breasts, fatigue and of course no period.
Nothing until 8 weeks. I found out at 4 weeks.