Mean transformation time for HIV to AIDS is:
Ref. Textbook of Microbiology and Immunology BY Parija. Page. 580
 
This is a straight forward question. Answer 10 years
Lines from WHO

The length of time can vary widely between individuals. Left without treatment, the majority of people infected with HIV will develop signs of HIV-related illness within 5–10 years, although this can be shorter.
The time between acquiring HIV and an AIDS diagnosis is usually between 10–15 years
Definitions of Long Term Non-Progressors, individuals were considered to be long-term nonprogressors if they had been infected with HIV for a long period (≥10 years), their CD4+ T cell counts were in the normal range, and they remained stable over years without receiving cART.
7.5 years
10 years
15 years
12 years