Had the same thought last night anon.
Found this.
Post #370
Dec 18 2017 20:57:15
Anonymous
ID: d3b6f7
121553
What happened on 12/7?
Dec 18 2017 20:58:04
Q
!UW.yye1fxo
ID: 82d434
121559
>>121553
Clock started - 10 days.
Q
Well in that post Q is responding to an anon that is asking what happened on Dec 7.
And Q says that the clock started.
So my feeling is the clock started on Dec 7, but not sure what the 10 days means.