Each animation key in a step has a start time and an end time associated with it. You set these times as percentages of the step duration, not in seconds.

The start and end time percentages for animation keys specify where on the step duration timeline an animation starts and ends. The timeline starts at 0% (time = 0 seconds) and ends at 100% (time = duration seconds). To calculate the start or end time in seconds, multiply the start or end time percentage by the step duration.

For example, suppose you want an animation to start half way through a 6-second step, and then end when the step ends. Set the start time of the animation key to 50% (3 seconds) and the end time to 100% (6 seconds).