As others have said, it's a matter of personal preference. Here's what I do...
I save the media file with my own naming convention... year, type of census, town/city, name of head of household
Example - 1940 US Census - Boston, MA - John Doe
I then create a source/citation with the same name style.
This allows me to keep like "raw" media files together on my hard drive before I link it to FTM. I can then easily match it to the source/citation when I'm ready to load.
To each their own... find a style you like & stick with it. I changed mid-stream when I realized I was losing information and then had to go back and correct everything. UGH!!!!