Why does it take 3 months until you find out hiv in your blood?

The average window period for HIV is generally considered to be 3 to 6 weeks, although it can be shorter or longer in some cases. This means that it can take up to 6 weeks after exposure to the virus for antibodies to develop and become detectable in a blood test. During the window period, an infected person may not be aware that they are carrying the virus and may still be able to transmit it to others.