Honestly this game looks awesome but when it will be released by Mihoyo ? Well i don't know either but I might have a guess when and we all know it's 2020.
According to Google search results it says Inital Release Date which only shows the year, not even of the month and day. But on the other hand platforms are already get stated : PC, PS4, Android, IOS, Nintendo Switch. Those platforms releases will be different from each other maybe by few days or even a week or two.
Currently we are in the closed beta which means only a month or two away from release or it will be released in Q3 2020.
I created a poll for the purpose of guessing the release time, anyone can vote and this way estimates can be made by community.