Because of your son's age you are unlikely to find a nursery that will take him - you'll need to enroll him in a full-on "school" that has a preschool - e.g. Compass, DESS, American School, etc.

There are plenty of South African expats here, but as far as I know there are no schools that teach Afrikans (sp?) or cater specifically to South Africans.

Good luck!