The person appointed as an agent in a disposition document may sign the disposition document at any time, but the agent's authority to act is not effective until the agent signs the instrument.
AS 13.75.040
Agent's appointment
Known as the Disposition of Human Remains Act
The act spans §§ 13–13 (14 sections).
Official source: Alaska State Legislature. Reproduced from public-domain Alaska statutes; confirm against the official source for the current text. Not legal advice.