When a bank is large, like Wells Fargo, you may have to do a little digging to find out who the actual contact person is regarding your short sale. It may be that they are also engaged in checking out the "clear" title...finding any leans and such on the current property, prior to going forward with an accepted price from a buyer.
Four to six weeks would be a conservative estimate.
Good luck with it. Short sales are known to be difficult.
I'm an Evanston Realtor and am just finishing up a short sale (I represent the seller) with Wells Fargo as lender on mortgage and home equity loan. The BPO agent has 10-13 business days to get the BPO to WF. Then WF does the analysis and presents it to whoever holds the loan (usually investors.) Then a decision is made. My best advice is to have your agent ask the sellers agent to call the Status Update phone number daily to see what's happening, and keep track of how long it's been since the BPO was done and inform the status person if it's taking too long.
Hope this helps.
Baird & Warner Evanston