Again, completely new version of Time Keeper will help your presentation by keeping your time.

Time Keeper Mark 3 is available for iOS7 devices.

Time Keeper will tell you the time you can set during preparation and the actual presentation. You can choose sound, vibration or voice notification. The color of frame tells you how long you still have time.
When you present something within a specific time, don't forget to set your Time Keeper that tells you the time by vibration in your pocket.
If you want to know the time with cooler looks, it's the time to connect your Bluetooth headset and you can get notification from it.

It's not difficult to use Time Keeper. And Time Keeper is completely free for iPhone and iPad without any advertisement.
Why don't you try?