Matt Smith was reported in January saying that he would start rehearsals on February 13th, with filming starting on the February 20th.
Karen Gillan also had this to say about leaving the show.
"It was a mutual decision between me and Steven Moffat over a lovely dinner actually. We both opened up about where we were at with it and then came to the conclusion that this was the best time to go." She added that she would miss working on the programme but was looking forward to other projects. I've had the most fun, so that makes me sad to leave, and I've made my best friends on the show as well. But it's time to go on to other things and all stories come to their natural end so I'm excited."