Compare Date fields: How to ensure that Finish Date is at least equal to *or after* Start Date, and *not* before?

To ensure that the Finish Date is at least equal to or after Start Date, and not before; we should follow these steps:

1. Add a Number field to your form (Label: Difference)
2. Go to Conditional Rules and add two rules
   1. Calculate difference between two date fields:
      1. Conditions: When both date fields are present
      2. Action: Evaluate

         differenceInMinutes({{date_2}}, {{date_1}})

         and set the result to the Difference field.

   2. Show message is difference is negative:
      1. Condition: If the value of the Difference field is negative (less than 0)
      2. Action:
         1. Disable Submit Button (e.g. Disable Element .btn)
         2. Show an alert message (e.g. Show Element #my-message)
3. Of course, you will need to add the alert message with the Form Builder > Snippet field:

<div id="my-message" style="display:none">Finish date should be equal to or after the start date.</div>

That’s it.