Many things determine this. A punishment appeal is usually answered by the person who gave the punishment. Depending on what timezone this staff member is in, how often they get on the forums, and how available they are when the appeal is made, it can take anywhere from less than a day to a week. If they are available, then it shouldn't be more than two days tops to get an answer. It will only take a week or more if they are on vacation or something related.