How early can you get pregnancy symptoms??

I didn't get any symptoms for 10 weeks with my first but I got symptoms straight away with my second child even though they say you can't get symptoms that early. 

I didn't start getting any symptoms till 6 weeks. Prior my symptoms were very much like period symptoms.

As crazy as it sounds I got symptoms with my first child early even to the point I couldn't really eat what I usually would eat without getting sick .. My period wasn't even late and now my daughter is 3 I had no idea I was pregnant but notice things was off days after sex ..everyone is different