I asked this question earlier:
Details.. we didn't have sex, but we were both naked, and his penis wasn't in me (no condom also), but there.. so i could feel it down there. We'd been playing about for a bit, and ok, i was wet, but i don't know if he was..? Would this have any affect on me or is this me worrying over nothing?

And one of the answers mentioned something about an STD eg Herpes.

The above happened last night, and i was just wondering if i were to get an STD, how long would it take to show up??