Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from West Palm Beach to Thera as you normally would.
Due to multiple factors, expect to potentially pay more when booking in June. For low rates, March can be a great choice for travel to Thera. Flights to Thera from West Palm Beach in March are about $926 on average during March, but can be found for as low as $391.