Run this script as administrator.
This script will do the following:
It will download 8 files, 1 image for each weekday and 1 script (see below).
(the downloaded files are in this repository)
It will create a task (see Task Scheduler) to run the downloaded script every time you log in.
The script will check which day it is, and then proceed to change your wallpaper to the corresponding image.
i.e
If it's monday, the script will set C:\Users%username%\WeekdayWallpaper\Monday.jpg as your wallpaper and lockscreen image.