In August I flew LUN-JNB on Airlink with a 3 hour connection to UA to EWR. Airlink checked bag through and it literally took longer to walk to transit area than it did to navigate security and passport check. Still had to wait almost 45 min at transit counters for UA check in. Then another security to enter terminal and still had enough time for shopping in Out of Africa and to pick up 2 bottles of amazing SA wine! You should really have loads of time. Botwsana is my next destination and I hope you have a wonderful trip.