To successfully walk you only need enough points to cover the two highest point-cost nights that will exist during your walk, i.e., typically two weekend nights.
What walking does at 11-months out is prevent anyone from reserving the room you have for the nights you already have and any future nights. Thus with enough points for two nights, you can begin a walk and succeed as long as you modify your reservation daily to drop a night and add a night. The only thing that having enough points for 7 nights adds to the equation is that the owner with that many points needs to modify only every 6 days.
In other words, if for example, I started a walk today, Sep 25, 2020, by reserving both Aug 25 and 26, 2021, I could successfully complete a walk to any period just as well as someone with enough points for 7 nights who started a walk today reserving Aug 25-Sep 2, 2021.