This is a serious situation and you should know before the auction what your responsibility is... don't leave it to chance and be pro-active. Know your rights and be prepared. Good luck to you and keep your head up high!
The amount of time varies by lender but it is usually 5 days. I work with several different banks and REO companies and 5 days is a pretty accurate average.
If you are referring to an auction by a private company, that date all depends on what the seller has negoiated with the auction company and agreed to in their contract for sale.