How to schedule an email using an event date property

Hi @josem7,

Welcome to the Community. 

You can try create a date triggered flow and have it trigger 1 day before the date of the event following our Guide to Creating a Date Property-Triggered Flow.

Or, our date trigger works on the profile level rather than the metric level, this means within your API Call Payload you will need to make use of the Profile Properties section in https://developers.klaviyo.com/en/reference/track-post e.g:
 

{
  "token": "PUBLIC_KEY",
  "event": "RegisterTest",
  "customer_properties": {
    "$email": "abraham.lincoln@klaviyo.com",
    "DateProperty":"1409592848"
  },
  "properties": {
    "title": "TestPage",
    "URL": "www.TestURL.com"
  }
}

You would then link the date triggered flow to the DateProperty property and get it to trigger 1 day before that date takes place
 
I hope this helps,

Alex