No official date, yet. My guess is probably sometime in late August or September. It will only be about half a season, though. Then, the Christmas special introducing the new companion. SPOILERS! Then, the rest of the season.

As an aside, a recent Radio Times poll had the Weeping Angels winning "best Doctor Who monsters of all-time" with a whopping 49.4% of the vote. Daleks fell to second with 17%. Third through fifth were The Silence, the Master, and the Vashta Nerada. Moffat creations took three of the top five spots!