I would not recommend getting the test done at JNB if all you have is three hours. But, there are two testing kiosks at the airport on the second floor that open at 8:00am - 8:30am depending. Their turnaround was about two hours. But you will not be allowed through passport/Customs until the test is complete and that can leave you little time.
If you are traveling through JNB from another country, then you must also go through passport/Customs and that can take 20 - 40 minutes depending. Then you take your test and then go back through passport/Customs and that can take another 15 - 20 minutes.
So two options:
1. Get it before your arrive JNB
2. Learn how to edit a PDF file
And for what it's worth - US Customs does not check your PCR status when you arrive - it is only checked on the foreign side.
Last edited by STRSWilson; 05/02/22.
