Go to Jamb.org.ng. www.jamb.org.ng or directly go http://www.jamb.org.ng/MockExam/CheckMockCentre on the page, you'll enter your Email/Jamb Registration and click Check details. That's all. That's the best way to check so far.
As at Saturday the 8th of April, was a day fixed to write the mock exam for already registered candidates, but on reaching to their venues, they said Mock exam was postponed to further notice. Jamb will relate a New date that would be convenient for all to write the mock exam they say.
Below is a format Of The Mock slip