A Way to Rename a Set of Files in a Folder from 'A to Z'

Pardon me if this is already posted somewhere here, but I've done a search for "Alphabetical Rename" and the posts that came up don't really match my situation.
I simply need to rename a set of files in a folder that I've dedicated for the renaming. That folder may have less then 26 letters of the alphabet in numbers of files. However, it will always be capped at 26 files.

So, if I have 8 .jpg files in it, and the folder is set with "Sort by name", Opus will rename the files, sequentially A.jpg, B.jpg. C.jpg. etc...
By the way, I always have the aphabet letters in the beginning of the names. So, essentially, it's almost like stripping the rest of the characters out of the names.

A third party utility like Bulk Rename Utility do that super quick, However, sometimes I forget to have it open or have to clear it from other renaming tasks; It becomes a constant switching :face_exhaling: Having this in Opus (where I could possibly map it to a button) would save tons of seconds that in times become minutes, as I need to do the renames over and over for a long period.

Anyhow, if someone could let me know how to make it happen or point to a solution that may already exist here in the forum, that would be very appreciated.

Thanks!

"Almost like" or exactly like?

Renaming a file to just its first letter is easy:

Great! That works.
You made it look easy. I need to take a deeper look into this Regular Expressions thing so I can do the same. :smiley:

Thanks!