Booking Calendar add-on for Google Forms

1. Introduction 

Step 1.

Booking Calendar is an add-on use for Google forms. It permits form's respondents to book the appointment from the form's admin' Calendar.
The add-on auto loads the events that the form's owner has created on the selected calendar under the rules that were set on the add-on interface. In the publish mode, the form's respondents can select and book an appointment via the form. Receiving the respondent's response, the add-on process the data then adds the respondent as an attendee of the appointment slot that was booked by him.
We expect that Booking Calendar will be a useful add-on.
2. Setup Steps 
Step 1: 
- Select appointment calendar with the notice that the calendar has some events that create as appointment slots [1].
- Select (or create then select) a drop-down field of the form then the add-on will load and add the calendar events as drop-down's choices [2].
- Active the form "Collect email addresses" feature or create an Email address field in short answer type. Let sure the add-on select the respondent's email field correctly then it can add the respondent as an attendee of booking appointment [3].
Step 2: 

This step is how the name of the loading events will be presented.
You can select one of given formats [4] or try your own format by checking the "Custom text format" [5].
Step 3: 

Step 3.

This step set the amount and condition to load appointment slots.
- The suggestion number of appointments is smaller or equal 10 [6].
- The add-on will hide the event that receives enough amount of invited or accepted guests following the admin's setup [7].
- The add-on will hide the too close upcoming event following the admin's setup [8].

That's all. Let save the add-on, wait a bit then check if it loads the events to the drop-down or not. If Ok, go to the form publish mode to test your own submission with another email input different the Calendar's owner' email. If the respondent is added to the selected event it's finally successful.