If I am taking a trip over 30 days out, do I have to pay now or can I pay closer to the trip date?

The process on Rover is that payment is required when you book with a sitter. Having to pay in advance is not all that unusual in many industries. During peak holiday periods, customers might book months and months in advance to get their sitter because there is often a shortage.

Your alternative is to wait until whatever time you are able to pay and see if you can find a sitter then. But do not expect a sitter to hold dates open for you without having a confirmed booking.