Simply set up your schedule and let Timey Timer guide you through it.
Other than most agenda apps, Timey Timer works with a specific start date and time and adds the duration of every additional part you enter.
To be in sync with a greater team, you can also export and share your schedule with others — even across time zones. In addition to the timer itself, there are visual and spoken aids: The app will flash green every 5 minutes before the next change, yellow at 1 minute, and orange on the transition itself.