The Red Devils boss is excited by the prospect of adding the former Real Madrid winger to his squad after an €84 million move but is not expecting miracles.
The Argentina international sealed a British-record €84 million transfer to Old Trafford on Tuesday, shortly before the Red Devils were thumped 4-0 in the League Cup by third-tier MK Dons.
Van Gaal is excited about deploying his new man all across midfield but urges patience from fans expecting big things right away from their marquee signing.
The Dutchman told Sky Sports after the match: "[Di Maria] shall contribute very much in our way of playing. He is also a creative player. I can change the system with Di Maria because he can also play on the wing and in midfield.
"I think that he can contribute and that's very important but we don't have to expect that from tomorrow.
"He has to adapt to the culture of England and the Premier League and to the philosophy of Manchester United."
The Argentine winger, who will wear the Red Devils' famous No.7 shirt, recorded the biggest goal haul of his career last season, with 11 strikes in all competitions for Madrid.