PREGNANCY SYMPTOMS

I'm just curious , I know they say you feel symptoms after like 2-3 weeks of conception , but how many of you knew and felt symptoms like after 3 days of conceiving ?? Like some women just knew like a few days after having intercourse that they were pregnant . If you guys are the same , how and what exactly changed that made you just know right off the bat . And did you get any of the symptoms earlier than they say is expected ?