What's the effect of setting timeOffset when animating?

The CAMediaTiming Protocol defines a timeOffset property. Now, they say it's a time offset. It sounds straightforward, but howefer, when I set it to 15.0 for example, the animation still imediately starts. The timeOffset doesn't seem to have any effect.

Maybe someone can point that out a little bit?

From stackoverflow Thanks

• The timeOffest property changes the starting point of the animation to a time other than the beginning.

  Lets say you have an animation with a duration of 5 seconds. Normally your animation would run from time 0 to time 5. If you set a timeOffset of 2, your animation will start out at time 2, reach time 5 and then 'wrap around' and run time 0 to time 2.

  To delay the start of your animation, use the beginTime property.

  From Jonathan Arbogast