The $8,000 First Time Homebuyers tax credit ends sooner than you think. It is published to expire "before December 1, 2009" which is technically correct. I think it's wise to plan to close on or before November 20, 2009 because that is the last Friday before the week of Thanksgiving which is historically a tough time to close because many in the real estate industry take vacation during that week. If you wait until after Thanksgiving you only have one day left.
Since it takes some time after the time needed for a pre-approval to get a contract fully executed, and then some time to actually close, NOW is the time to get your First Time Home Buyers pre-approved.