Oh, this is SUUUUUUUCHH a great question!! But, I'm not exactly sure what you mean.
When we, as agents refer to an offer being "contingent", it generally means that the BUYER has submitted an offer to the SELLER contingent upon the sale of the house they currently own.
But, I'm wondering if you mean an offer presented to the seller that's "contingent" upon bank approval, meaning the seller's lender has the right to decide whether or not that first offer is going to go through because the sellers are doing a short sale.
Which is it?? Because these 2 scenarios would have very different answers!! :D
Scenario #1 would be accepted, rejected or negotiated within pretty short order, generally within a day or 2. Scenario #2 has NO time line that anyone can quote with any certainty. The banks take as long as they take. Sometimes the buyers on the first offer just lose patience and withdraw their offer, but that is more difficult to do these days without that language being written in to the contract.
Does this help???