What you could do is create a bunch of shortcuts to all of the files, and then launch all of them from shortcuts.
Say your documents are in C:/docs/january, C:/docs/february, and C:/docs/march. Make a new folder called C:/docs/shortcuts. Select all of the files in the january folder, right click, select "create shortcut". Move all of the shortcuts to C:/docs/shortcuts, then do the same for february and march. Now you can select all of the shortcuts in that folder and launch all 3 months at the same time.