Better logic calculate time

[DirkG]

If not done yet, you can also have a look at the official post of the “iCalendar to Voice” app, maybe there are some ideas to solve your problem.

iCalendar to Voice by Raymond Brink [not supported - use IcalCalendar]

I use it every day to start car warmer. I have several flows checking outdoor temperature 120, 90, 60 and 30 min before appointment with the name “Car warmer”. But if you are trying out you need to consider that the app checks calender with the interval set in the app. And I have noticed that I need to force update from mobile calender after setting new appointment.