I notice that currently, when using the date sort order for the thumbnails, it sorts by the PID column rather than the CTIME column.
PID is not really a date and only matches CTIME order if you don't change your CTIMEs

However, what I would like to see is cpg picking up the date/time from the jpg file and storing that in the database and then being able to use that to sort by. The date on my jpgs are the date when I took the picture.
Somebody else asked about changing the filenames whilst in the system. This could be done in the "Edit Pics" section. You would just need to modify the filename on the disk and then update the table for the new filename. This same section could also be used to change your picture date/time if you needed to.
I'm new to cpg, but if I get some time, I can look into doing these changes.