That is a very good question without an easy answer. Short sales can take from 2 months to 10 months. Every one of them have different characteristics that influence the process, i.e. bank, how many loans, listing agent, and the sellers, etc.
If the listing is actually showing as "pending" then there is a good chance that the bank has already accepted the offer and they are proceeding under normal contract terms. If the bank has not accepted the offer yet, it will generally be listed as AWC (active with a contigency). The best thing to do to get an accurate answer is to have your agent contact the listing agent and check the actual status. Not every agent updates the MLS correctly and timely.
With all that being said, most short sales that do not have an accepted offer by the bank will take "back up" offers. These are generally held from the bank and will only be presented if and when the pending offer is declined. If you submit an offer before the first one is presented to the bank, the agent may submit both (several), or ask for "best and final" of all interested parties and then submit the highest offer.
I know this may not have directly answered your question, but I help it hopes a little.
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