there is no thing called "average" when it comes to a person. or a person who has knee surgery. every person on this planet is different when it comes to their ability to deal with pain and not all knee surgeries (or the surgeon performing them) are the same either. so there are no "average times" for pain duration. the only person that could give you a rough estimate would be the surgeon who did the procedure -- someone who is familiar with the case and someone who knows what kind of surgery that was done.
what is the average time a person will have pain after knee surgery