PHP 8.6 alpha 1 is out. The announcement asks us to test it and report issues.

Most teams will wait for the stable release before trying it. That makes their first contact with 8.6 coincide with the moment they want to upgrade.

Add the alpha to CI as an allowed failure. A dependency may refuse to install, or a test may expose an assumption about the runtime. Finding that now gives the PHP ecosystem time to respond and leaves your own team without an upgrade deadline ticking in the background.

An early CI job also shows how much of the deployment is actually declared. Perhaps the application passes while the image cannot build because an extension was added manually years ago. That problem already existed, and the alpha made it cheap to find.

Run it somewhere harmless and see how much work "later" already contains.