At the 2023 SOTU. Some folks claim he would have been a lame duck but let's face it he already was with the house being in R hands. All of his signature legislation was passed in first two years of his term. The 2023 SOTU should have been used as a victory lap for that and announcing he was keeping his promise to be a transitional president.
And I am not only blaming him, I am blaming all D leaders (specifically Clinton, Obama, Pelosi, Schumer, and Jeffries) for not sitting down with him after the 2022 election and making that case to him. To the point of saying if he doesn't announce it they will make sure there is a public outcry for him to do so. Basically what happened in July of this year should have happened 18 months earlier.