If you want to buy at the courthouse auction you will need all cash the same day.
If you're not an ALL CASH buyer you will have to wait until the property is listed for sale. You can't buy from the bank --except at the courthouse or if you are buying a whole portfolio of properties for at least hundreds of thousands of dollars.
Find an agent to help you and if you're in Ohio you will have to bid blindly because the abosulte best deals are bank-owned properties listed by lazy asset managers who will not even let the house sit on the market for a week and will just take the first offer on the first day that is close to the asking price. It's purely negligent and I'm surprised the underlying investors on these properties are not requiring a minimum 7 days on the market to allow it to sell for "market price".