Janiah,
There is no stock answer unfortunately it will all depend on the apprasier. If it is an FHA or VA loan it may even take a little longer. So once the apprasial has been ordered and then after they get out to the house it should realistically not take more then a week at the most for the appraisal to be back in the hands of the bank. The problem most people are running into right now is that there are so many first time home buyers out there that everyone is getting very busy and they are all behind. So keep in touch with your agent and the lender and that way you can stay on top of the situation.

Hope this helps,