Most people after exposure will test positive after between 2 and 12 weeks. There is a small percentage of people who will not test positive until the virus has been in their body for 6 months, so to be absolutley sure that you are HIV free, take the test at 6 months after exposure, but feel free to take the test before that; say, at 12 weeks because this fits the time frame for most people to have the virus show up in their blood. Let’s put it this way, if it were me, I would get tested after 12 weeks and again at the 6 month mark.
If you live in the United States, there is a National HIV and STD Testing Resource Center that will direct you, based on your postal code to the nearest testing center. If you chose the finger prick method to test for HIV, it is called the RAPD test and it will give you the results within 5 to 60 minutes of the procedure. Standard testing takes up to 2 weeks for results to come back. There are tests that you can buy online and in drug stores to do yourself, but only one is approved by the FDA and is called the Home Access HIV-1 Testing System. This test involves pricking your finger, squeezing blood onto a prepared card, then mailing the card into a laboratory for testing. Counseling resources are available to you before, during and after the procedure.
If you live in Britain, you can contact the British Association For Sexual Health and HIV. Type in your postal code, and the website will show testing centers near you.
If you live in Canada, you can contact the Public Health Agency of Canada for a 1-800 number specific to your province or territory.
In South Africa, The Aids Foundation of South Africa can direct you contacts who can help you find test locations.