Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Spokane to Jeddah as you normally would.
These are just IATA (International Air Transport Association) codes. They are used in aviation to identify and differentiate airports. That’s why a Spokane Airport to Jeddah King Abdulaziz Intl Airport flight would often be abbreviated as a GEG to JED flight.