Start With Countdown Timer (pro mode only)

Use the Start With Countdown Timer command (from the Advanced Timekeeping submenu of the Edit menu, or press Ctrl+F5) in Day View or any multiple day view, to Start an item and also launch a Countdown Timer for the item's duration, all at once.

This command otherwise is identical to choosing the Start command, and then the Countdown Timer command, so for full explanations of each, please refer the help topics for each of those commands.