When would I get a reliable test

Ash

How long after unprotected sex would I be able to get an accurate STD testing ? I don’t know if it won’t show up in my blood & urine if it’s too early or if it would automatically be detected. I read online it takes 3 months to get a reliable test but I don’t know if I’m getting symptoms of an STD or not. I’m really confused and I want to understand what’s happening to my body right away.