Hello. What are the punishment for not waiting until marriage ?
If you are speaking of punishments administered by an Islamic legal system, in the overwhelming majority of cases there would be no punishment because people are encouraged to keep their sex lives private even if it is sinful. If they are discovered by their families, their families are also encouraged to keep things private and to forgive them and let them go on with their lives like normal if they repent and to not make it public.
Legal punishments only happen in the case of someone flagrantly airing their sex lives in public; if a person is discovered in the act of copulation by four witnesses and 2. there is a legal system in the country or state that enforces Islamic law and 3. the four people choose to testify in court against them rather than keeping silent, then those convicted would be publicly flogged then let go to go on with their lives. This means that the Islamic legal system ends up dealing almost entirely with cases of prostitution, rape and what may be called debauchery (orgies, etc.) rather than cases involving normal people’s lives, which are left to people’s own discretion.
If you were asking about God’s punishment for a person who engages in premarital sexual relationships, then it is sufficient for them to repent and stop doing it for them to be forgiven (as explained here).