.play()

Begins playing forward, optionally from a specific time (by default playback begins from wherever the playhead currently is). This also ensures that the instance is neither paused nor reversed.

If you define a "from" time (the first parameter, which could also be a label for TimelineLite or TimelineMax instances), the playhead moves there immediately and if there are any events/callbacks inbetween where the playhead was and the new time, they will not be triggered because by defaultsuppressEvents (the 2nd parameter) is true. Think of it like picking the needle up on a record player and moving it to a new position before placing it back on the record. If, however, you do not want the events/callbacks suppressed during that initial move, simply set thesuppressEvents parameter to false.

//begins playing from wherever the playhead currently is:
myAnimation.play();
//begins playing from exactly 2-seconds into the animation:
myAnimation.play(2);
//begins playing from exactly 2-seconds into the animation but doesn't suppress events during the initial move:
myAnimation.play(2, false);