How accurate is hiv test 8 weeks post exposure? and 10 weeks?

Probably 100%: The main HIV blood tests in use in the US are virtually always positive by 8 weeks, even though some agencies advise waiting until 3 months after the last exposure. The "4th generation" or "duo" test, for both HIV antibody and antigen, is conclusive any time 4 weeks or more after exposure. However, the oral fluids test sometimes takes as long as 3 months.