Need Help Triggering An Automation Before A Google Calendar Event

I need help figuring out how to trigger an automation before the start time of a Google Calendar Event, I know how to use the offset feature “!!-30” but this is for a shared event and I don’t send out the invitation, so I can’t use that.

I’ve read this thread “How to trigger automation BEFORE set time” but it uses time and a temperature value that I’ve tried to remove but have not been able to get to work successfully.

I’m trying to trigger a TTS automation if there is an event with a start time in the next 36 hours. The start time value I’m trying to check against is


I want the automation to run at 10:00 AM and if the start time of the next event is within 36 hours a TTS script will run. The condition part is the part I’m struggling with.

alias: Announce Next Meeting
  - platform: time
    at: '11:00:00'
  - condition: template
    value_template: |
  - service: script.tts_announce_next_meeting_office

I was in a similar situation and came across your thread, you can check my post on how I resolved it for me here: