An HIV test detects the presence of HIV antibodies, not the virus itself.
It takes between six weeks and three months for the body to develop enough antibodies to be detectable by the tests currently used in Québec. This is referred to as the window period. If you get tested for HIV within this period, the test results will most likely come back negative. Because of that, your healthcare professional will usually ask you to come back for a control test a little while later, to confirm the results of the first test.
If you have high-risk anal sex in January, get tested in April
If you have high-risk anal sex in January and February, get tested in April and May