IINM (not a safe bet), BO has delivered a set of engines to ULA, but they haven’t been fully tested. However, it allows ULA to move forward with Vulcan assembly (they can do fit tests, hook up the plumbing, do some integration tests, etc.). A second set of engines is almost ready and will go through the full round of testing before delivery, and I think those will be the first flight engines.
Or not. Honestly, some of the reporting around this is a little confusing, and as always the jfb filter must be taken into account (turns signal into noise).