Preferably, It is best to enable three-5h of transit time in Johannesburg, so that you have sufficient time to catch your connecting flight. Transiting in Johannesburg is very simple; only follow the symptoms for ‘International Transit’. The flight from Johannesburg to Harare normally takes about 1h 30m. By clicking 'Acknowledge', https://www.theluxurybooking.co.uk/flights-to-zimbabwe-from-london/