If they don't approve that offer they will likely set a short sale acceptable price for the agent to take back to the marketplace. Just know that there is no standard answer necessarily. It's frustrating for buyers, agents, and escrow officers. Hang in there.
Also - sometimes the Short Sales aren't always the great 'deal' they seem. Sometimes you can find a motivated, traditional seller. That way - you have an answer in 48 hours or so.