Beginnings, Part 1 & 2 will air as a one hour special on October 18th. Although we are getting a one hour special, there will be a two week break afterwards. Korra will resume airing normally in November starting with episode #9, The Guide which will air on November 1st. Episodes are now airing at 8:30PM EST on Nickelodeon!
Source - The linked source if very legitimate and has supplied correct Korra leaks for months, they have an inside source over at Nickelodeon.