Use DateDif with IF statement

[Johfra]

So far, I have: =datedif(consult date, today's date, "D") which calculates what I've needed, up till now. Now, I want to expand a little more, I want it to stop counting if I have given an appointment.

consult date = 2017-05-02
today's date = 2017-05-23
days pending = 21
date of appointment = 2017-05-26

I want it to stop counting if there's a date in the appointment column

I'm not sure what formula to use because "today's date" changes daily....

Thanks.

*correction made 2017-05-23 @ 10:44am

[Special-K]

Your subject says DATEDIF, your description reads "ifdated" and makes it look like a macro rather a standard Excel function??