The matter was postponed to May 12 before Judge Johann Daffue.
Prinsloo, 51, from Springs, Gauteng, faces charges of treason and conspiracy to take part in terrorist acts, as well as possession of illegal ammunition.
Prinsloo, Mark Trollip, 48, and Martin Keevy, 49, were arrested in connection with the alleged plan to attack delegates at the African National Congress’s conference on December 16, 2012.
Trollip has already pleaded guilty to a charge of conspiracy and was sentenced to eight years in prison last year. In October, Keevy was declared unfit to stand trial and declared a patient of the State.