(fuck yeah, actual discussion!)
Is it too early? Absolutely. Though I find nothing wrong with hyping it up early on. It's better than having it come out of the blue, that's for sure. In retrospect, I liked the subtle building up to the Marineford War. As for Big Mom, again, I'm still not sure if Luffy will actually beat her or if their fight will come to a conclusion. Some aspects of OP are pretty obvious, so who knows what may happen with Lola's vivre card- assuming BM is her mother.
I'm also not sure about Emperors being stronger than all the Warlords. Sure they're powerful, but I doubt they're the absolute strongest. For BM and maybe Kaido, I assume it's an influential/worship sort of hiearchy, resulting in a huge ass crew. There's still Doflamingo and Mihawk, and one of the greatest things about the OP-verse is that it comes down to match-ups as well as not always having obvious power levels. Enel and Crocodile, even to this day are still formidable opponents. Taking DBZ (Frieza, Cell, etc.)/Akatsuki and damn near everyone else in Naruto for example, they've all fallen off the wagon of who appears to be strong. There's a level of consistency in unpredictable power levels in OP.
But yeah, it's still too early for Doflamingo to get taken down. I expect Law to get hit hard with his arrival though. There needs to be repercussions after the shenanigans Law/Luffy pulled in this arc.