Booking your trip from Riyadh Airport to ETH at the last minute could save you a tidy sum if you happen to find a good deal. However, tickets don't usually get cheaper closer to the departure date. If you hold off, flights could also be booked out or the best seats taken (don't get stuck in the middle!). If you'd rather not take any chances, book well ahead of when you want to leave. Note that some of the biggest deals can be found up to 12 months in advance. If your preferred airline hasn't released tickets yet, check back regularly as deals are updated on Expedia all the time.