I am thinking I won't actually be 70 1/2 until early 2012.

You must take a mandatory distribution by April 1 of the calendar year after the later of (a) the calendar year you turn 70-1/2, or (b) the year you retire. You turn 70-1/2 in January 2012, so you must start withdrawing by April 1, 2013 (unless you have not yet retired as of Dec 31, 2012).