You can sometimes book a hotel as late as the day before check-in, but most of the time, you’ll want to book well in advance. You can see what’s available up to 40 days in advance, and even monitor the price trends if you’re not ready to book right away. Prices tend to go down the closer it gets to the date, especially around the 21-day mark. 21 days from your check-in, prices are generally somewhat normal, with prices often falling, then briefly rising, then falling again. Last-minute bookings can be especially cheap since hotels are desperate to book their …