Stream aside...the teaser appears to state 9/21. And TWIP posted this today 9/21: "TWIP will have a comprehensive overview and deep dive regarding deeproot Pinball’s launch later today.
We also plan to include an interview with Robert Mueller. Keep any eye out for the post later today!" So something had to be planned for today.
Seems like deeproot need to get something out before the day is over. To delay due to a fake countdown and to counter your own teaser seems very short sighted. If the plan was for today sometime they need to make that happen.