While the news may spread, I could see the actual bounties not being raised until after Wano (assuming it's no more than a few weeks to travel to Wano).
Since we're likely getting the Reverie next -or at the least about to happen around this time- logistically they may just decide that having a meeting to discuss their bounties will take unnecessary Naval resources away that the WG may need for the Reverie.
I mean Luffy's first bounty had decent sized meeting between some Marines. For something this big, I'm sure it's certainly possible for them to postpone their bounty discussion. And of course if something happens at the Reverie, like Blackbeard or Dragon showing up, that would likely delay the Strawhat bounties from rising.
So yea, I'm pretty much expecting no raise until after Wano ends. In my opinion this would make more sense with both the timeline of events and in terms of the story beats. I just don't think Oda is going to give a bounty raise for defeating a Warlord, then for crippling an Emperor's family and operation, and then for -at the very least- contributing to whatever chaos will result from their clash with Kaido's crew in Wano.
On the flipside, given that Wano is an isolated country and it seems right now that all the parties that we know will be involved don't have direct ties with the Navy themselves, I could see the information about whatever happens on Wano not being spread to the rest of the world. This way Oda can still give a bounty raise and make it known to the public that the crew is messing with the top four, while not having to add yet another raise for doing the same thing just a few weeks later(in story time).
So that all said, my ideal preference would be for the news of this current arc to be made public, with the bounty discussion being pushed until after the Reverie. Whatever happens at the Reverie will take the WG's attention away from the Strawhats for a little while, just as the Wano Arc sets in. Leaving with the Crew getting a raise after Wano, either accounting for Wano's ending or the bounties rolling out just as the news of Wano breaks. I mean, we have the top news guy himself in this arc specifically covering the news of something that would likely not spread outside of Totoland. And the next Emperor the Strawhats are going to face is specifically in a country isolated from the rest of the world.
Was there not an increase after him defeating Doflamingo? I feel like there ought to have been but if there was it would have to be at least 750M and I don't think I'd forget a number like that being stated. But with that, defeating half the Sweet Commanders, being the captain of the crew who fed Big Mom a coma-inducing cake (presumably), and recruiting rogue former Shichibukai Jimbei, Luffy's definitely got the chops to be worth a billion at this point. So if the next official increase is postponed til after Wano, it'll have to be well over a billion by then.