Just because you have a csection doesnt mean anything different other than a baby came out of your stomach instead of your vagina. Your cervix still opens to release everything and you can contract an infection super easily. Which can lead to issues with future pregnancies and long stays at the hospital.
That being said, I ignorantly attempted sex at 3.5 weeks PP. It was the most painful thing Ive felt. Worse than my contractions. It was as if my cervix was badly bruised and it made me feel sick to my stomach . I will never do that again and I suggest you wait.