Actually it should take a couple of days just from the particular time an underwriter receives a loan file to provide approval what you really refer to as an official approval. But if in case your file is having any problem related to credit score or any document related issue than it may take much time to approve. For getting an official approval for a loan would take 3 – 4 working days to be underwritten. I’m talking about 3 -4 days only if all your documents are completed and fit according to the wants. Else, it would be a long procedure, as the process is going start away from a new end.