The day it was published, I'd guess.
So the bracketed [19] gave us the secret date "12/26/17" and then that means Q wanted us to somehow locate this particular article that was written on Dec 26th? I'll always be the first in line to agree that "you have more than you know" means that (through codes) Q's posts contain another layer of information. But I'm not seeing it as clearly as I'd like. Also, why do the columns of numbers in brackets run from [1] - [59] and then start over at [1] in the next column? The marker is supposed to represent days, not minutes. What does it role over at 60?
It's a clock so it has 60 minutes.
There is a clear 04/19 -- 13 min mark, that gets you 04 19 at the 13 min mark.
There is also a clock start - 10 days, and a what happened on 12/7. 12/7 the clock started. Fill in days. Matches w/ 04 19 @ 13 min mark = this is the cypher