The key dates are:           

Friday, November 30, 2012:           Official Screen Credits due
Saturday, December 1, 2012:           Governors Awards presentation
Monday, December 17, 2012:           Nominations voting begins
Thursday, January 3, 2013:           Nominations voting ends 5 p.m. PT
Thursday, January 10, 2013:           Nominations announced 5:30 a.m. PT, Academy's Samuel Goldwyn Theater
Monday, February 4, 2013:           Nominees Luncheon
Friday, February 8, 2013:           Final voting begins
Saturday, February 9, 2013:           Scientific and Technical Awards presentation
Tuesday, February 19, 2013:           Final voting ends 5 p.m. PT
Sunday, February 24, 2013:           85th Academy Awards presentation