The current W7Y ARM 2.0 (as listed on the SOTA association page) was updated Aug 31, 2022 and states Dec 1 - Mar 31 which is in line with the summit info.
An older (superseded) W7Y ARM v1.05 Issued Feb 12, 2014 that does not feature on the association page but can be obtained via a google search states Nov 1 - Apr 1.
A reflector post makes reference to further pending changes.