The average onset of AIDS after exposure to HIV is 10 years. A person infected with HIV who never received any treatment would start getting very, very sick at that time. Without any treatment after 15 years, a person would have died.
Several volunteers on other forums who are HIV positive themselves and are receiving ongoing treatment have confirmed that, once they tested positive for HIV, they would always test positive (similar to mono).
Surely anti bodies be detectable from 4 weeks and still as that for ever , with new tests like 4th generation test also can detect p24 antigen which work in opposite with antibodies mean when the test can't detect antibodies it must detect the p24 and if don't detect both that means the person is negative