I have found that once the bank has aquired the property and has it listed, you can usually get an answer within a week. Most will want you to sign the banks addendums and the p&s within 48 hours of acceptance allowing no changes to be made to the paperwork. The common snag is obtaining a clean title. Often times the title search will uncover issues that need to be addressed before the bank can legally come to the closing table.
You should take TerritoryRE's advice and find yourself a good Buyer's Agent that has had experience in bank owned properties. Make sure your agent does a market analysis, I have had three recent encounters where the bank has foreclosed and re listed the home 15-25k higher than what the previous agent was trying to get for a short sale.