Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Orlando Airport to Changsha as you normally would.
Located just 15.2 mi from the city center, Changsha Huanghua Intl is the airport most travelers will use when flying to Changsha from Orlando. Booking flights from Orlando to Huanghua Intl (CSX) should be relatively easy as there are 0 daily inbound flights from Orlando from 0 different airlines.
Orlando Airport is MCO and Changsha Huanghua Intl Airport is CSX. These codes are created by the International Air Transport Association (IATA) and airlines use them to identify the departing and arrival airports in the flight routes they service.