When I started using systemd timers, I really liked the systemd-analyze calendar facility, to calculate n trigger times for a given calendar expression.
For example, show the next five trigger times for the end of the last day when the month has 31 days :
For example, show the next five trigger times for the end of the last day when the month has 31 days :
systemd-analyze calendar --iterations=5 '*-*-31 23:59:59'