Trigger sun offset conditional not work

Good night everyone.
I would like my automation to start at sunset or an hour before it depending on the month we are in.
I wrote this:

    - platform: sun
      event: sunset
      # D'inverno parte al tramonto, altrimenti un'ora prima
      offset: "{{ iif((now().month in [1, 2, 3, 10, 11, 12]), '00:00:00', '-01:00:00') }}"

But there’s no way to make it work…

offset doesn’t support templates

You’ll need to trigger at both sunset and an hour before, and use a template condition to decide whether to continue.

I assumed so…

Thanks for the confirmation