At this time, anyone able to build from source is encouraged to pull from master and test the code. Ideally try to test as many of the functions of the CLI and/or GUI as you are able, not necessarily just the common ones you normally use.
There will likely be a testnet rollback or restart at some point so the forking code can be tested as well as the post-fork consensus code (K12 proof of work and fixed ring size). Stay tuned for announcements on this schedule to help with testnet testing.
Perliminary binaries before tagging for easier testing
https://www.reddit.com/r/Aeon/comments/cxeacs/perliminary_binaries_before_tagging_for_easier/