Well My dad's 485 got Approved in Dec 2004. and i filed the I-824 from Texas Service center on May 12th 2005 (Recept Date)... and i got Approved on May 31st 2005...
So thats 19 Days... the approval says We have notified the consulate listed above that the applicant's Status has been adjusted to that of Lawful permant resident.

So thats 19 Days... the approval says We have notified the consulate listed above that the applicant's Status has been adjusted to that of Lawful permant resident.