See, then this is pointless. When you ask if something is priced in then all you are asking is "what is the price right now".
By your definition, there is never, ever an answer. Nothing is ever priced in, because we have no idea what future demand looks like. It is much less tangible -- especially because of the multitude of variables and the inability to isolate the effect of any one event on future demand. Perhaps the first reward halving will be "priced in" two years from now. How would we know?
The bitcoin exchange markets are not sophisticated enough or liquid enough to have much "priced in." I would speculate that <5% of any rumor is ever priced in before it is news.
And once it is "news" I think a lot of speculators in bitcoin exchanges are not leading the action, they are following it. The market is too volatile to try to lead. And most dont have the financial leverage to take those risks. Therefore, if the news generates new money into the markets, there is a delayed effect. That effect is then further "priced in" or "over priced in" once the speculators start following the action.
So, in China, there have been news stories for months. Money finally found its way into the market and started leading. Speculators then drove the price up through the roof.
Who are speculators following? Are they not following other speculators?
I don't think money "finally found" its way to the Chinese market because of news circulating for months... Speculators drove the price up overnight, probably based on Baidu news.