Ideally, you should allow for 3-5h of transit time in Johannesburg, so that you've got ample the perfect time to catch your connecting flight. Transiting in Johannesburg is very uncomplicated; basically follow the signs for ‘Worldwide Transit’. The flight from Johannesburg to Harare will take about 1h 30m. Delayed my https://www.theluxurybooking.co.uk/flights-to-zimbabwe-from-london/