What computer operating system is your Premiere Elements 12 running on?
Sorting in the Premiere Elements 12 Editor Expert workspace Project Assets is restricted to by name or by duration if you use the Premiere Elements 12 Add Media/Files and Folders route.
However, in the Elements Organizer 12 (which comes along with Editor), you have sort by choices of oldest, newest, and name.
In the Elements Organizer 12, consider creating Album(s) of your files with sort by of oldest and/or newest. That will order the files in the Album in a date/time sequence. When needed, bring the Album into Premiere Elements Editor with the Editor's Add Media/Elements Organizer.
Once imports are in Editor workspace Project Assets, you can create folders in Project Assets to further organize. And, the List View of Project Assets can be used to move files in and out of folders to create different ordering effects.
Please check out the above and let us know if any of that worked for you.
Do not hesitate to ask questions or to ask for clarification.