Actually I need to correct myself. The timeframe for when you catch a STD and the time is possibly shows symptoms is the "incubation period". The time from when you catch a STD and the time you actually can test positive for it is called the "window period". You can still catch an STD from someone infected even if they do not test positive for it if the test was conducted during the "window period".Very true and even if you have a test 30 minutes before, they can still have and pass along a STD that has not shown in the test yet if they just caught something during the incubation period.