...2024 is it's own election, and if he were to take over as President on January 23, 2023 to complete FJB's term, Trump would STILL have to run in 2024 for his next term.
I don't think it's a problem for him to announce that he is running again in 2024. And, I also don't think that that would be a "game changing" announcement tonight.
Just my opinion.
Announcing a run is not a concession. But it can inspire even more voter turn out tomorrow. It would be very smart.