15.5 months for B performer and 16.25 months for A performer, but it's very hard to get A, I only gotten A twice throughout my 8 years.

Promotion is very limited cos one section probably only need 1 principal. Some may not get to be principal in this career lifetime. On average, my section takes 10 years to be promoted from JG12 to JG13. I foresee perhaps 15 years for me to promote to JG14, if it ever happens lol.