I didn't remember that date, however Karen Gillan just tweeted it to let us know, and accompanied that tweet with an even better picture, their first ever camera test together.
1st pic of Matt and I in character was released 4 yrs ago today, but, I have the real one..from the 1st camera test pic.twitter.com/72ldPCvpM3
— Karen Gillan (@KarenGillan2) February 18, 2014
It's made me really miss them :-(Might have to stick on the series 5 box set in a minute.