Trending @Accenture; Promotion for level 12

Hi guys, Can someone tell me what is the promotion criteria for level 12 employees. Earlier it use to depend only on months at level, like if you have completed 21..24 months then you are eligible. But, recently i have heard that "months at level" is changed now. Now it is only 15 months, and after that you are eligible. Anyone, from management level, or HR people please help me with this.