You mentioned that there are two loans on the property. Do you know if the two loans are through the same lender? Generally speaking, once the appraiser goes out to the property, you can expect that it will take some time for the negotiator to send out a letter of approval which will outline where the money will be going in relation to each party (first loan, second loan, title, agents, etc) if the short sale is approved. In that case, the second loan will then begin their review of the file once they know they will be allocated a certain dollar amount. They can still deny the short sale at that time.
If time is of the essence for you, I would speak to your agent as soon as possible. You would need to review your contract thoroughly to see what the reprecussions would be, if any, for canceling the contract which would be good to know should you decide to submit an offer on another property.