Pandora was the first entire Land that opened in ages. NFL was the last and it was different, being an expansion and in the middle of an existing land. They didn't have an Passholder previews for it but they did pull in folks as they were in the area for soft openings. Since TSL is more like Pandora than NFL I'd expect to see them do the same as with Pandora.
Not sure anyone who truly knows is talking about what they'll do for sure though