How would someone know if a date is already taken?

When making a request is there any automated response that "this date/time is taken"?

I believe we still don't have a specific solution for this.

But you can try a workaround by using Reservation Form app that is more directed to seat reservation, but it can work, or you can use a Zapier Integration that allows you to use  Google Calendar.

In addition you can use the Gift Registry widget. You can see and clone  the test form:

http://form.jotformpro.com/form/41415596592967

I forwarded this request to our developers so they can consider this feature implementation.

They will notify you via this thread once they have an update on this.

I have developed Date Reservation widget - it lets every date be chosen by one user only, days already reserved by others will be unselectable. I hope it will suit your needs.