Oral sex exposes you to gonorrhea, syphilis and herpes. Most experts agree with the fact that chlamydia is not known to be transmitted through oral sex.
7 days after the exposure they can star showing symptoms, but sometimes, stds don't show any symptom at all. You can test as follows :
-Gonorrhea, 3 weeks after the exposure.
-Syphilis, 6 weeks after the exposure, and if you get it negative, you should test again 3 months after the exposure, as there are people that take longer to show a positive result.
-Herpes, 3 months after the event.
You were given antibiotics as prevention, but it would be interesting to test anyway.
All the best.
Ususally gonorreha and chlamydia are tested together