Answers:
It vary on the STD. Some you can examination for sooner than others.
Incubation period rise and fall so it depends on the exam.
A Student Health Services doc from the University of California, Santa Cruz, indicates the following:
Chlamydia - results will be positive by 7 days after exposure
HIV - try-out will be positive 6 weeks to 6 months after exposure
For more information click on STI FAQ Information Sheet in the STI/STD Screening Forms partition http://www2.ucsc.edu/healthcenter/forms/...
This Planned Parenthood website also give carrying out tests info.
http://www.plannedparenthood.org/rocky-m...
3 to 4 months after but you have need of at lowest possible 6 month to grasp a polite reading