He palms the bag with his arm fully extended until 4 seconds prior to the final boarding call. He then pum-fakes until 3 seconds prior to the fasten seatbelt sign is on. At this point, he passes the diminutive suitcase to a flight attendant who scrambles to find an open spot in an overhead compartment before the plane takes off.
I bet Stuckey doesn't even look when he puts his bag in the overhead bin. He just slams it up there, colliding it into all of the other bags.