Here is part of a memo posted from another website.
“In addition to the printed menus available on board, the digital menu is available for all cabins on all flights. A general menu will be viewable up to a year in advance so customers who are booking flights can see what kind of experience they can expect, and the actual menu will be available anywhere from 75 to 45 days before departure once the menu is finalized. The menu can be viewed while in flight. On flights with meal service, please make the following announcement to encourage customers to view the menu: “If you would like to see what we’ll be serving on board, today’s menu can be found on united.com or in the United app for your convivence. Simply navigate to Flight Status > Inflight Menu.”