I agree with Jenna.
Speaking as a landlord I never made appointments to show my property more than a day or so out, if the prospective tenant and I were available at some point during the day they called, I would try to show it then. As a renter I never made appointments more than a day out, because like Jenna mentioned, you run the risk of losing a place you had your heart set on, and if I found a place I liked, I learned the hard way to sign a lease (or at least put in an application to hold the place) that very day if possible, lest you run the risk of losing the place as well.

no more than 1-2 days away from when you want to see it. because the rental market is so unpredictable- you can make an appointment to see something a week or 2 out, but the likelihood it will still be avail is slim-

and as a landlord if person A made a applointment on feb 14th but person B wanted to see it today- I would show the rental today and accept a depeosit, NOT waiting for the appt on the 14th. this is just how it works.