So I am running timeline to show sub-menus:
var tl = gsap.timeline( { paused: true } );
tl
.to( cc, { duration: 0.5, autoAlpha: 1 }, "start")
.to( menu, { display: 'block', duration: 0.5, autoAlpha: 1 }, "start")
.to( li, { duration: 0.1, opacity: 1, stagger: 0.03 }, "start");
Menu is set to display: none; by default. The "display:block" is applied at the end of the animation.