Track View > Dope Sheet > Time: Dope Sheet toolbar > Insert Time button
Use Insert Time to interpose time into highlighted tracks. Inserting time adds time at a selected point in your animation, making existing keys slide out of the way.
To insert time into tracks
-
In Dope Sheet mode, highlight one or more item labels in the Controller window to specify tracks for time editing.
-
Drag in the Key window to insert time into the tracks.
Tip: To insert time globally, highlight the World track, turn on the Modify Child Keys button, then insert time into the World track.