How long should i wait before having an aids test after having sexual intercourse (for the virus to be detecte

75% of people will test positive by 17-20 days after infection
95% by 2months
>99% by 3 months
and virtually everyone by 6 months (this last category includes people who --before they were exposed to HIV-- had a condition that resulted in immune deficiency like cancer treatment, organ donors on anti-rejection drugs, etc.

3-6 months later. it may show up after 3 but sometimes not til after 6months

What would be detected is the antibody to the virus as it takes quite some time for the virus itself to be detectable. If you are concerned with the possibility of exposure, call your doctor to schedule a test. Chances are, you will be put on a routine schedule for testing. Finally, you should do what you can to reduce/eliminate risky behavior that could lead to exposure.

The health screening guidelines established by the Singapore Ministry of Health recommends the HIV blood test be done 1 month, 3 months and 6 months after a high-risk exposure. The need for repeated blood tests is to rule out false negative results.
More information at http://www.health-screening.sg/hiv-aids....

I stand by vee-leef and yzzf's answers.

I agree with the last answer. I have known people to have it show up earlier than most say. Also, from personal, recent, expereinces, there are new tests that are available and more sensitive than older ones. Just last night I was reading about a PCR test that is looking directly in the blood for the dna of the hiv virus itself- unlike the normal test that just looks for antibodies. The link below has lots of good reading when it comes to this serious topic. It's very stressful to go through but remain calm and don't over think it. If you do, your mind will take over- look towards family/friends or even support groups if need be.