"how long does it take for threads to be approved or dissapproved"
I am assuming you are talking about the Rom-hacking section, correct? If so, you will have to wait for Semele or Blazichu, the resident moderators, to log on and decide if it meets community standards. If it does, your thread will appear shortly after. However, if it doesn't show up for a few days, it usually means your thread didn't make the requirements.