Reykjavik is 5 hours ahead of Medellín
Best overlap: 8:00 AM to 1:00 PM in Medellín is 1:00 PM to 6:00 PM in Reykjavik.
Your shared working hours run 8:00 AM to 1:00 PM in Medellín (1:00 PM to 6:00 PM in Reykjavik). You've got a decent 5-hour window. Set a recurring time near 8:00 AM in Medellín (1:00 PM in Reykjavik) and stick to it.