If the hours are equal, you each pay half. If you have unequal hours, you calculate based on whatever rates you've established with your nanny. The pros and cons of hosting more or less cancel themselves out, in my experience. You don't have to get your child ready and go anywhere, which is a luxury both for convenience and for time. But you do have another child in your house each day playing with toys, have to store gear, have more utility costs, etc.