The best time to start with the pre-qualificaiton is really...now.
Why? Because you'll have your credit report pulled from 3 credit agencies, and,
what if there is an error there in their reporting, or something is not reported properly?
Then - you'll need to fix the issues, clean your credit, possibly apply for additional cards (
to have a higher available credit limit)...you might need to pay off some past debts like collections,
or medical bills or just to pay down your car loan below 10 payments (this will increase your buying power)...
There is the additional money that you might need to set aside for the purchase - for inspection,
downpayment, closing costs, home & flood insurance policy, insurance inspections...and reserves (leftovers to show that you'll be ok for at least 3 months worth of payments).
So, if you start now, you'll be in a much better position later on - and ready to roll!
By then - you'll also need a pre-approval letter from your lender (the difference will be in
providing full documentation for loan approval-but without the actual house).
Pre-approval is a must have when buying a property.
Hope this helps,
Beachfront Realty, Inc.