The cheapest day to book a flight, hotel, or vacation package on Expedia—or any other travel booking platform—can vary based on a few factors, including the destination, time of year, and specific promotions available. However, some general trends have been observed when booking with Expedia:
Source: https://support.google.com/googleplay/thread/306015267?hl=ru&sjid=11050229069584416965-AP