Hi ALiska, What you are attempting to do is labor intensive and can fail to properly keep your pictures in order. Try doing this instead, and your pictures will always be in date, numerical and alphabetic order.
2009 Photographs (folder/directory)
200901 January 2009 (folder/directory)This is how I teach people to keep all kinds of files. Obviously, the first thing is the date in a reverse format... YYYYMMDD
20090101 January 1, 2009 (folder/directory)200902 February 2009 (folder/directory)
20090101-001 (picture file)20090105 January 5, 2009 (folder/directory)
20090101-002 (picture file)
20090101-003 (picture file)
. . .
20090101-123 (continue picture files)20090105-001 (picture file)20090131 January 31, 2009 (folder/directory)
20090105-002 (picture file)
. . .
20090105-123 (continued picture files)20090131-001 (picture file) . . .
20090131-123 (continued picture files)20090202 Groundhogs Day (folder/directory)20090202-001 (picture file)
. . .
20090202-123
This creates file or folder names that are always in ascending numeric order by date of creation.
This Christmas would be 20091225
After that you can use the name of the file and within dates, it will be alphabetic.
Maybe my schematic wasn't clear, but if you browse my hd (I didn't want to post a screen capture of the tree structure), you would see that they all fall in chronological order and always will so long as I don't make a mistake.
It might be a little labor intensive, but I just add the new years, months and days as they occur which only takes a minute or two. I'll make sure I understand your system, basically I do, and can convert to that easily enough but a little labor intensive to make the change initially. I always retain the photo numbers assigned by the camera(s).
My first camera I could instantly tell the dates and year from the photo number. The 20D (and others in that series) just assigns IMG_xxxx.CR2 (or .jpg when I was not shooting in RAW), and builds on it numerically. In my work files, I usually but not always try to assign unique mnemonic names to my finished output so I can find them a little more easily.