There is always an excitement and enthusiasm as new stable releases start showing up on the downloads page -- and that is great! As of this moment, 21.02.3 and 19.07.10 are currently building, but they are not complete nor are they announced (current versions are still 21.02.2 and 19.07.9). Over time, the 'current' and upcoming versions will be different, but the same principles apply.
A few things to know before you try to install new versions prior to the official announcement:
The build system may still be running, and it is a pretty big job. It typically takes several days for everything to complete. The official announcement will come after everything is done.
Because of the fact that the builds take time, you may find that some targets/platforms are ready and others are not. This will almost always resolve with time as the build progresses.
The same is true with user-installable packages -- it may appear that packages are missing, but really they just haven't been built yet.
There is a relatively small chance that a problem will arise during the build process that may cause the build to fail. If this happens, the dev team may need to fix the issue and begin the build process again. Although it is quite unlikely, it is plausible that this could even include a major bug,
For all of these reasons, it is not recommended to install a new version before it is officially announced. And, if you choose to install, just remember that things are potentially still in flux, including packages you might rely on.