How to start multiple VR movie at the same time when operated in different PCs

Hi! We're making a VR movie that can be played in a museum. We will have 12 people watching, wearing 12 different Oculus headgear and each one of them will be plugged into 12 individual computers.  The problem is that we want the movie to start at the very same time. Is there any way to achieve this? Please help if you know!  Thanks in advance :D