I think it can be almost as early as 2 weeks after you conceive but most symptoms will be when you are about a month
I'm 2 months pregnant I'm only 14 I had unprotected sex and I start having symptoms about 3 or 4 days after we had sex
Theres no way you can get symptoms at 4 days sorry.
When I was pregnant, I started 'smelling' things before we even knew for sure I was pregnant. Air fresheners, etc made me ill. It varies, but I think it can start pretty early.