Not really when it is ready but when graphics overhall for tracks and the new tyre physics have reached the test patch phase in development.
I believe the high level ultimate plan is to have those and the day-night transition to be released in test patch same time or at least very near each other.
But as we all know there is no timeline communicated when all this will happen.
@hondacivicc Please use google translator or ask your countrymen to translate it for you