The couple were reported to be tying the knot on August 11, the same date as Pitt's parents Bill and Jane's golden wedding anniversary.
The actor has apparently flown a team of builders to their home in southern France to get renovations finished in time for the wedding, which has been moved to late September.
Pitt has even chosen the placemats for the reception and hymns for the service, which will have just 20 guests - much less than the previously-expected 300.
"Angelina isn't so bothered about when they tie the knot - it's Brad who is piling on the pressure," a source told The Sun.
"He wants the main house to be finished when the event takes place, even though the close friends and relatives who are invited aren't the types to care.
"He wants everything to be absolutely perfect."
Their children - Maddox, 10, Pax, 8, Zahara, 7, Shiloh, 6, and twins Knox and Vivienne, 3 - will be heavily involved in the wedding ceremony.