The Secretary of Labor shall issue a proposed rule under section 911(a)(1) of the Social Security Act [
42 U.S.C. 1111(a)(1)] (as added by subsection (a)) within 12 months after the date of the enactment of this section [
Feb. 22, 2012], and shall issue a final rule under such section 911(a)(1), after public comment, within 24 months after such date of enactment.