All situations are different. You situation is not specific, so in general responses can vary a great deal.
For example, if the home has not yet been approved for a short sale, it could take weeks. Once it is approved and the price set, it may take a few days.
It all depends on the lender and the manager assigned to that case. The better the listing agent, the better it will go.
I agree with Erica's response. It takes awhile and is somewhat unpredictable depending on who you get assigned to your file. I have had some come back with 5 days with a verbal ok. Others have take an amazing 60 days. Key is for the agent to stay pleasant, organized, and willing to fax things over and over and over and over again. : )
-Call and see if you can obtain a contact name, phone number, fax number and e-mail address of the short sale negotiator who is assigned to your case
-Call frequently early in the morning before they are stunned with calls
My last short sale response was 12 days for an answer. I received a verbal "probably will work" within 2 days and then another 10 days went by before I received the approval in writing.
Every office and agent is different. If you need help, there are short sale negotiators. Others I have spoken with experience more like 30 to 40 days to get a firm response.
In my experience, the key is relationship building with the contact person. Whomever answers the phone, work on developing rapport so they will go the extra mile for you.
If all else fails, elevate with assistance from the real estate professional, attorney, or negotiator you bring in to help you.