Preferably, you need to enable three-5h of transit time in Johannesburg, so that you've got ample time and energy to catch your connecting flight. Transiting in Johannesburg is very quick; only Keep to the signals for ‘Worldwide Transit’. The flight from Johannesburg to Harare usually takes about 1h 30m. Off-peak https://www.theluxurybooking.co.uk/flights-to-zimbabwe-from-london/