How much should I charge a client for housesitting 2 days and half a day?

I booked my first client today, whooooo! They need someone to housesit for 2 and a half days, but they only put 2 days on the booking. To be more specific they will be home by 5pm on the 3rd day. So, how should I change it so that I am charged for the 2 days and most of the 3rd day? Also, how much did you charge for sitting less than a day?