Nairobi is 1 hour ahead of Milan
Best overlap: 8:00 AM to 5:00 PM in Milan is 9:00 AM to 6:00 PM in Nairobi.
Keep meetings inside 8:00 AM to 5:00 PM in Milan — that maps to 9:00 AM to 6:00 PM in Nairobi. With 9 hours of daily overlap, these two cities are an easy pairing; almost any reasonable hour works. Remember that Milan shifts for daylight saving and Nairobi doesn't, so recalculate the overlap after each clock change.