Keep in mind that you don't need to use 1 CS and 1TS and 1 snack each day, you can use (for example) 2CS and 1TS and 2 snacks on one day. Also note that you don't get credits per day, but as Mickeefan said, you get credits per night, so there even if you don't eat at all on the day you arrive nor on the day you depart, that's just 1CS, 1TS and 1 snack extra to use on the other days, assuming you'd tend to use your credits evenly in the first place.