Timeline for Promotion from CL9 to CL8 and Salary expectation

Hello all. Just wondering a general timeline for promotions. I heard someone say that the average time is around 2 years at current level. Im coming up on a year and will be starting a new role. Can I expect a promotion at the end of this year, or more likely mid-year of next year? Also if so, what percentage will be expected for a raise? Thanks in advance.