How and When Are Dings Offered ?

[wee-haggis]

I was wondering how SWA decided when and under what circumstances to offer DINGS.
Is it as simple as waiting until X number of weeks before certain flights are due to leave and seeing if all fare categories are selling ?
So, for example if there was a similar situation to the photo I've attached, DINGS would be offered at some point ?

 

[Rella Bella]

I don't think there's anyway to know in advance what will or will not be offered. It seems completely random. They probably have some formula, but I can't imagine we'd be able to tell from the website.
Now if your best friend worked for SW...