Shenzhen is 6 hours ahead of Athens
Best overlap: 8:00 AM to 12:00 PM in Athens is 2:00 PM to 6:00 PM in Shenzhen.
Your window to reach both cities is 8:00 AM to 12:00 PM in Athens, which converts to 2:00 PM to 6:00 PM in Shenzhen. The shared window is roughly 4 hours; treat its midpoint as the default and you'll keep both teams happy. The difference isn't constant year-round: Athens adjusts for daylight saving while Shenzhen holds steady.