It’ll be new. Therefore it will be popular.
Slinky Dog will become the new ride that is hard to get, though not as hard as FoP, which I’m sure will continue to be tough for up to 60 days +3. Just like 7DMT and FEA plus the new Soarin for a while. Almost certainly it will become tier 1. Not sure if they will re-tier anything else’s at that point, they definitely will when SW:GE opens.
With Pandora, they released fastpasses when they announced the opening date. It was within 60 days if I recall, but outside the 30 days. No soft openings at all, until possibly the last couple of days before the official date, and then totally unannounced and usually just for 30 minutes if I recall, not enough time for social media to alert the masses! However they did morning to night AP pass holder and DVC previews, (I think only for those with onsite reservations) and also announced extra Pandora-only EMH for 2 months or more.
With 7DMT they did soft openings instead.
Anyone’s guess at the moment what they will do this time. You will probably just have to re-plan when they announce it. if they do back to back previews there won’t be time for soft openings, so that will be what to watch for.