You didn't have a risk for HIV. Sexually, HIV is transmitted by having unprotected anal or vaginal sex. It would not matter if saliva was on the condom prior to inserting the penis anally, since saliva is not infectious.
In any case, 28 days is recommended as a conclusive testing time unless you have had a real exposure with someone who is HIV+ (in which case you might want to test to 42 days, for peace of mind).
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