The GDE's online admissions system went live at 8am on Monday.
Parents said they were pleased by the speedy process, with some applauding the department for offering assistance at the Diepsloot Youth centre as they were unemployed and did not have internet access at home.
Gauteng Education MEC Panyaza Lesufi said there could be some delays with the system due to the high numbers of applications, urging parents to keep trying until they completed their applications.
The online admissions system was initially meant to go live a week ago and the department had to delay it following letters by some stakeholders who raised concerns regarding implementation of the newly amended admissions regulations and feeder zones on the system.
Parents have until midnight on July 22 to apply, and have been urged to apply on time to avoid disappointment.