Can you start seeing std symptoms not even a day after unprotected sex?

Maybe: Depending on the infection, the symptoms may occur from 1 day to 3 weeks after exposure. If you do have symptoms such as unusual or foul-smelling vaginal discharge, vaginal itching or ulcers or bumps - you should see your doctor to be tested. You may also consider getting treatment for the most common stds right away just to be on the safe side.