As a reminder, here the AAS Policy on Postdoc positions:
The AAS Council has passed (1988) and reaffirmed (2003) a resolution stating that no postdoctoral position should require a candidate response prior to February 15 of each year. This policy applies to postdoctoral positions whose recruitment cycles follow the normal academic search timeline (offers in early spring to begin summer or fall of the same year). The text of this resolution is available on the Council Resolution webpage. Employers should take this policy into account in their recruitment process.