Returns the most recently added child tween, timeline, or callback regardless of its position in the timeline.
var tl = gsap.timeline();
tl.to(e1, {duration: 999, x: 100, repeat: 5}) //very long tween
.to(e2, {duration: 1, y: 200}, 0.5); //insert this tween at 0.5 seconds (toward the beginning of the timeline)
.to(e3, {duration: 1, scaleX: 2}, tl.recent().endTime() + 3);//inserts the new tween 3 seconds after the e2 tween which was added most recently.