Robert Niles of TPI had an article a couple of weeks ago. His Universal sources are generally trustworthy and he generally only releases info when he's sure of it (or has been given the OK). He said he's just seen the blueprints and the scene after the huge screens scene include a massive Kong AA. from Niles, "Kong appears on the right side of the ride track as the ride vehicle curves along Kong to their right, allowing a long moment with the Big Ape". So, he's saying you're still in the tram when the Kong AA makes it's appearance. In this scenario, it would clearly be before the riders disembark from the vehicle.