I don’t think ever. Twitter has too big of a brand name and recognition, where X does not, and they’ll keep coasting on it (their emails to you still say “formerly known as Twitter”). News sites and places will keep calling it Twitter because X is too confusing of a name, and certain parts of their reader-base will simply have no idea who it is that they’re on about, and some social media will call it Twitter because X is a silly name, and they do not respect Elon Musk’s rebranding of Twitter in much the same way that he does not respect his daughter’s name or identity.