Condoms work very well to prevent HIV transmission.
HIV is not passed to the receiver in oral sex even without protection, so you do not need to worry about getting HIV from this encounter. You do not need an HIV test if this is the only risk you are concerned about. If you still want to get an HIV test, just to reassure yourself, you need to wait until at least 3 weeks after the exposure to get an accurate test. The most conclusive HIV test will be at three months after a risk.
You might be exposed to other Sexually Transmitted Infections like Gonorrhea, Chlamydia, Syphilis or Herpes from oral sex, though. You can take a look at our Know Your Chances – Oral Sex. It’s a good idea to get tested for these regularly if you’re sexually active. Using condoms for oral sex can protect you against many of these infections.
Let us know if that answers your question or if you need more information,