Reply To: half day / full day calendar booking

If you just want them be able to book the same day delete the departure field.
What I like to do in that case is to replace the hour select fields by a normal html select with the same name and id. And that selects only have two options, the first for arrival with for example 8:00 and 14:00 and the second for departure with 14:00 and 20:00.