Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Singapore to Pullman as you normally would.
Related info for your journey
Useful info, stats and facts about Singapore to Pullman flights.
These are just IATA (International Air Transport Association) codes. They are used in aviation to identify and differentiate airports. That’s why a Singapore Changi Airport to Pullman Moscow Regional Airport flight would often be abbreviated as a SIN to PUW flight.