If you don't have a pre approval the listing agent is not likely to even look at your offer , You see the pre approval process only takes a few very short amout of time depending on your situation. 

If you want the 3 bed 2 bath for a smoking deal it will not wait for you to get the below information together.  So why not do it now?

Some lenders are different but most are standard, the below information is very important when shopping for an REO (Real Estate Owned) home. 

REO Pre approval lender check list

General

•1.       Picture ID with Social Security Number

•2.       Payment to cover application fee

•3.       Name and Complete address of all landlords (past 2 years)

Income

•1.       Employment history, including names, addresses, phone numbers, and length of time with that company (past 2 years)

•2.       Copies of your most recent pay stubs and W-2 form (past 2 years)

•3.       Verification of other income (social security, child support, retirement)

•4.       If you are self-employed: Copies of signed tax returns including all schedules (past 2 years), and a signed profit and loss statement for the current year.

•5.       If you are retired: Tax returns (past 2 years)

Assets:

•1.       Copies of all bank statements from checking/savings accounts (past three months)

•2.       Copies of all stock/bond certificates and /or past statements / retirement accounts.

•3.       Prepare a list of major household items and their values.

•4.       Copies of title documents for all automobiles, boats, or motorcycles.

•5.       Face amount, monthly premiums, and cash values of all life insurance policies (Cash value may be used for closing cost or down payments.  You need documentation from the carrier indication cash value).

Creditors:

•1.       Credit cards (account numbers, current balances, and monthly payments)

•2.       Installment loans (car, student, etc.) Same details as for credit cards.

•3.       Mortgage loans (property address, lender with address, account numbers monthly payment and balance owed on all properties presently owned or sold within the last 2 years) bring proof of sale for properties sold. 

•4.       Childcare expenses/support (name, address, phone number).

Other:

•1.       Bankruptcy - bring discharge and schedule of creditors.

•2.       Adverse credit - Bring letter of explanation.

•3.       Divorce - bring your divorce decrees, property settlements, quitclaimed deeds, modification, etc.

•4.       VA only - bring Form DD214 and certificate of Eligibility.

•5.       Retirees - bring retirement and/or Social Security Award Letter.