GAT is conducted four times a year. Date of each schedule test is advertised in popular newspapers at least 15 days before the test date. You can find the schedule for your desired test date in NTS official website http://www.nts.org.pk/GAT/GATSchedule.asp. Keep in mind that test schedule is on the sole discretion of NTS and subject to change; we that is, the author and the publisher do not taken any responsibility for any change. You must consult NTS for any scheduled date.
You must visit official website of NTS for current schedule of the tests. You must start test preparation as early as about two months before the test date.