There are two date and time settings in RSVPify.
After you first create your event in RSVPify, we'll convert your start date to written text. This text can be anything you like, and can be edited in Setup > General Options.
By default, RSVPify will also include a calendar invitation that can be downloaded by guests after they submit their RSVP, and is also included in the email confirmation sent to your guests.
The setting for this calendar invitation, including start and end date and time, can be edited in Setup > Confirmation Page.