Gonorrhea and Chlamydia have a window period of 3 weeks. You can test any time after those three weeks, but I must tell you that chlamydia is not known to be spread through oral sex. So, if your only exposure was oral, you can really forget about chlamydia, but test for gonorrhea, syphilis and herpes. If this info helps, i will also tell you how to test for those two:
-6 weeks after the exposure, for syphilis.
-3 months after the exposure, for herpes.
How did you test for this? Local clinic or doctor's office via swab?