Nevermind, I figured out how to make a Lister auto-select the first file when entering either the D:\BEFORE folder and the D:\AFTER folder. I just added Select FIRST to the edit field for the hotkey entries I had made those 2 folders.
By the way, there are two interesting scripts, which do basically the same, letting you select specific files or folders, whenever you enter a folder. It's Leo's "Special Auto-Select", or tbone's "SelectEx" script. Just have a look at the "scripts" sections of this forum.