At the moment, the RSD process varies from a few months to many years. It is difficult to estimate how long your case will take so you should plan for it to take many years, just in case.
There is no way estimate how long the process will take. In very limited circumstances, UNHCR can accelerate the RSD process, but even then the process may take many months or years. After registration, most refugees are given RSD interview appointments four years away. Once you have been interviewed, it is not unusual for it to be 10 months or a year for a decision to be made.
If your case is initially rejected and you submit an appeal, it may be over a year or more for UNHCR to review and decide on your appeal. Again, there is no way to determine how long an appeal decision will take.