What is the simplest way to run a timer-triggered Azure Function locally once?

I had the same question, and used the DEBUG-flag to have the RunOnStartup only while debugging:

        public static void Run(
            [TimerTrigger("* 0 7 * * 1-5"
#if DEBUG
            , RunOnStartup=true
#endif
            )]TimerInfo myTimer, TraceWriter log)
        {