Use the full relevant history and applicable rules rather than assuming a single anniversary settles eligibility. Also verify the knowledge and proposed duties at the planned stage.
Review the timeline before fixing commitments
Earlier qualifying work may need assessment, while a new continuous period may be relevant in other circumstances. Do not promise a filing date without checking the actual foreign employment, intervening time and receiving organization. An anniversary is a date, not an eligibility test, and the two are confused often enough to be worth separating explicitly.
What the timeline has to show is a continuous qualifying year abroad falling inside the relevant preceding three years measured against the proposed assignment, together with the knowledge the role requires at the point the person would start. Both can move. A delayed start pushes the three-year window forward and may pull an older qualifying period out of range, while a reorganisation can change which entity employs the person midway through preparation.
The failure to avoid is a promised date announced to a United States team before either question has been checked, because withdrawing it costs more than waiting would have. Fix the earliest date on which the facts would support the assignment, then plan commercially around that rather than the reverse.