Medellín is 7 hours behind Johannesburg
Best overlap: 3:00 PM to 6:00 PM in Johannesburg is 8:00 AM to 11:00 AM in Medellín.
Both offices are open during 3:00 PM to 6:00 PM Johannesburg time, which is 8:00 AM to 11:00 AM in Medellín. You get roughly 3 hours of shared time, so aim for the middle of that window to keep the call comfortable for both teams.