If booking 3 months in advance for boarding, does rover hold the funds I pay & only pay sitter AFTER completing the boarding?

I want to reserve a sitter to board my puppy for 12 days. The boarding date is 3 months out. I am wondering if I make the full payment to Rover now, does Rover pay the sitter AFTER boarding is completed or NOW? I just don’t think it is a good idea to have the sitter receive a lump sum months before they perform the service otherwise when it’s time to perform the service it seems like they are doing it for free since it was so long ago that they were paid. Just would like clarification on how/when payment is provided to the sitter.