It all depends on the std and the person some people can get an std and have it for 6 months before seeing any symptoms others can start having symptoms sooner it all depends best bet is use protection always and get checked on a regular basis.
Most STD's do not present with symptoms. some common ones are iching, burning, redness, odor, discharge. you should always go in for a routine check up if your not sure.
Im not sure about symptoms surfacing, but if you go to the doctor to get blood work done for STD testing they say to do it at least 6 months after your most recent partner, because all STDs surface within 6 months, but Im not too sure for the ones that have no symptoms. I would advice calling a doctor or a telehealth line for all the complete details, or even do some online searches to find out.