That last sentence doesn't sound right.
If you have a December use year, you can't start a walk for December stays until December 1. Chances are you won't be able to start a walk that close to the desired dates.
For example, a stay of 12/7/22 - 12/14/22 falls in the December 2022 use year. Can't start a walk for that until 12/1/22, unless you are willing to end up with points stuck in your 2021 use year. By 12/1, others will probably already have blocked you from getting that first reservation you need to start the walk.
If you think you will need to regularly walk a certain reservation, it's best to have a use year that begins a few months prior to that stay.