As others have said it is common practice to pay the rental in full anywhere from 30 to 60 days prior to arrival. This is mainly because it is often more difficult for owners to find someone to take your place if you cancel.

Your rental agreement will clearly state what happens if you have to cancel after payment is made and the amount of refund, if any, you might be entitled to receive if you cancel so you should first look there for answers. The rental terms can vary from rental to rental but generally speaking the closer you get to your "arrival date" the greater your cancellation penalty will be. If you want to protect yourself against this type of loss you should purchase Trip Insurance that specifically covers this type of risk/occurrence. Understand too, that in many, if not all, instances you have to purchase Trip Insurance within a specified number of days of your initial booking - here again the time can vary - but usually it is within 10 to 20 days. For example, if you booked your reservation 6 months ago you probably won't be able to purchase Trip Insurance now for a trip you are making next month.