According to Allegiant Airlines Cancellation Policy you have as long as 24 hours from the time you first purchase your ticket for a discount on the off chance that you booked something like 2 days preceding flight. The 24-hour discount strategy applies to all ticket types, however you need to drop the excursion to get a refund. Reservations booked as a feature of the gathering block don't meet all requirements for the 24 hour discount. To know more about it read the full Blog.