Next alarm not triggered in automation

I enabled the mobile app next alarm sensor.
I want to use it as a trigger in an automation.
But apparently, the sensor is updated so quickly, it doesn’t get triggered most of the time (I have multiple alarms every day).

If the first alarm fires, I want to turn on a light.
I see a countdown in HA, but there’s no trace in the automation.

The automation (test):

alias: 'SLAAPKAMERS: wekker test'
description: ''
  - platform: time
    at: sensor.sm_g780g_next_alarm
condition: []
  - service: notify.mobile_app_sm_g780g
      message: de wekker gaat
mode: single