if you'd slept with someone who had herpes, how long would it take to know if you contracted it?

Im not sure but l think it can take a while, maybe just get a check up at planned parenthood or your dr

It depends on a few things. The level and type of the outbreak of the person you got it from is the first part, then there is your body is reaction and defense to the infection, as well as your immune system strength at the time of the infection. This question would be best answered by a doctor.

It could take years.