(Not supersonic yet - top speed 460mph (mach 1 = 761))

First flight Wheels-down (2 points, 6 months ago) https://news.ycombinator.com/item?id=45748035

Taxi tests (138 points, 9 months ago, 133 comments) https://news.ycombinator.com/item?id=44615033

Cleared for final assembly (90 points, 2019, 60 comments) https://news.ycombinator.com/item?id=21834889

I found a link that said they were discussing the testing schedule with media, but haven't found a timeline for when they might go supersonic.

First X-59 post on hn was 8 years ago!