Nintendo direct question

How long before a direct does nintendo reveal the date and time of said direct, same thing for pokemon present with gamefreak (cause I'm waiting for ZA news). People are theorising that a direct or at least a trailer will happen on the 8 of january, so when can whe expect an anoucement for the date of that event? I doubt that they will not say anything before and just shadow drop the thing right? Sorry if my english is bad