The work I'm doing on HSXsanity has taught me that averages across all movies (like the 10% rule) are useful sometimes, but frequently wrong for specific movies and need to be put in context. (The lower potential for weekday BO is a good example of this) But you really need to find like movies and compare performance.
But there simply are no good comparisons for GATSB.
The audience is a weird mix of Leo fans, Baz Luhrmann fans, 1920s/Gatsby fans, people interested in the soundtrack and people interested in the style of the film. There are few movies like it. BOM is usually pretty good at identifying similar movies, but they're comparing it to Django Unchained, Life of Pi, Magic Mike, Dark Shadows, Hugo, J Edgar, Bridesmaids, Wall Street 2, etc... None of these movies are anything like GATSB. If these are the best comparisons that BOM can suggest, there are no good comparisons.
The B+ Cinemascore is not a good sign, but OTOH the audience is varied and is looking for different things. I'm thinking fans of the book probably gave it a C, while people drawn in by the ads probably gave it an A+ (I'm guessing this because a theme of the book is about how living a life of excess doesn't make you happy. But the film is marketed as "Excess! It's great, and so stylish! Enjoy life!")
It reminds me a little of MAMIA, which also got a B+ Cinemascore, and had great word of mouth. Clearly enough of the audience thought it was A+, even though others (probably the poor souls who were dragged along to see it) didn't.
The drop on Saturday is a clear indicator of front-loading though.
Anyway, for Gatsby I'll adopt a wait-and-see approach until we get some more dats, but while I'm waiting and seeing, I'll be playing the players.