Hi Silent.
Only a blue can provide accurate information, but I can share what we know based on how we usually receive API changes.
There is no API for PTR/Beta so any API change will probably go live after the changes are patched in the retail version of the game. Once the APIs are live the official docs page are also updated to match the new endpoints.
Sometimes we receive a preview of how the new endpoints will work in a forum post, so it is worth keeping track of blue announcements over both D3 and the API forum.
You might want to join API discord server (if you didn’t already) and take advantage of the API blue tracker and announcements channel.