To view and edit design animations timeline:

•  Click on the bottom menu Timeline button.
• To close Timeline options, click on X or timeline button.

Timeline options:

1. Click on timeline object row to select that object.
2. Drag row corner to reduce duration
3. Drag full row to change object start time.
4. Click on  the right + to add time to timeline.
5. Drag orange seekbar to preview animation live at the current time.
6. Click anywhere on the timeline to preview animation stage at the click place(time).

(reference editor)