The remains of the world-famous surrealist, who is buried in his museum in Figueras, in northeastern Spain, were ordered exhumed after a woman who claims to be his daughter filed a paternity claim.
Pilar Abel, a 61-year-old who long worked as a psychic in Catalonia, says her mother had a relationship with the artist when she worked in Port Lligat, a tiny fishing hamlet where the painter lived for years.
A spokeswoman for the Salvador Dalí Foundation, which manages the artist's estate and has lodged an appeal against the exhumation, told AFP they had been notified by a judge that it would take place on Thursday, July 20th.
A spokesman for Madrid's high court, which oversees other courts in the area including the one that ordered the exhumation, added it was scheduled for 9.30 am local time (0730 GMT).
Experts will take DNA samples directly from the grave where Dalí was buried after his death in 1989, which will then be sent to Madrid to undergo the necessary tests.
But the foundation hopes to avoid it if its appeal is successful.
On Tuesday, medical experts extracted saliva from Abel to obtain her own DNA and cross-check it against that of Dalí.
In an interview with AFP last month, just days after a court ordered the exhumation, she said her grandmother first told her she was Dalí's daughter when she was seven or eight years old, and her mother admitted it much later.
Abel is from the city of Figueras, like Dalí, and she said she would often see him in the streets.
"We wouldn't say anything, we would just look at each other. But a glance is worth a thousand words," she said.
Notoriously eccentric, Dalí's life was marked as much by the genius of his work as by his own extravagances.
A question has always hung over his sexuality, with some claiming he was a closet homosexual who preferred to watch others having sex rather than taking part.
But according to Abel's lawyer Enrique Blanquez, his affair was "known in the village, there are people who have testified before a notary".