Can I get credit if I pick up my dog one day early? instead of 10 days it will be 9 days?

Please call Rover Customer Support at [Edit: Rover’s contact options have changed. Visit the Rover Help Center at https://support.rover.com/ to find the phone number, help articles, or chat with the team]. Any refunds are subject to the sitter's stated cancellation policy.

It depends on your sitter's cancellation policy. If you did notify her within the frame she states in her policy, you will be entitled to a refund. If you didn't, then you do not get a refund unless she decides she wants to refund you because of her good will.