Medellín is 18 hours behind Wellington
Best overlap: 8:00 AM to 12:00 PM in Wellington is 2:00 PM to 6:00 PM in Medellín.
If you set up a recurring sync, 8:00 AM to 12:00 PM in Wellington (2:00 PM to 6:00 PM in Medellín) is the natural home for it. You share roughly 4 hours a day. That's enough for regular meetings, but treat the window as prime time and guard it. This window straddles two dates — Wellington's today is Medellín's the previous day. Because Wellington and Medellín don't both observe daylight saving, plan to re-check the overlap around March and November.