The BBC have confirmed - via Twitter - that "Deep Breath" will air on BBC1 at 7.50pm on Saturday 23 August 2014.
The synopsis reads:
When the Doctor arrives in Victorian London, he finds a dinosaur rampant in the Thames and a spate of deadly spontaneous combustions.
Who is the new Doctor and will Clara’s friendship survive as they embark on a terrifying mission into the heart of an alien conspiracy? The Doctor has changed. It’s time you knew him.The 75 minute feature-length opener has bagged itself the same timeslot as "The Day of the Doctor" - the later the better as far as I'm concerned as I'm not a fan of early evening broadcasts. Previously, we've had to suffer through "Don't Scare the Hare" prior to "Doctor Who" - this year it seems we'll have to put up with "Tumble"...