Zurich is 9 hours ahead of San Diego
Best overlap: 8:00 AM to 9:00 AM in San Diego is 5:00 PM to 6:00 PM in Zurich.
The overlap falls at 8:00 AM to 9:00 AM in San Diego, or 5:00 PM to 6:00 PM if you're in Zurich. Because Zurich is 9 hours ahead of San Diego, the shared window is only about 1 hour. A fixed slot at 8:00 AM in San Diego (5:00 PM in Zurich) saves a lot of back-and-forth.