This is the number one question I get asked as a pest professional. The answer to this question is not simple. Everybody reacts differently to a bed bug bite. I have met people that don't have a reaction for two to three weeks. While others react almost instantly and some people won't react at all. A lot of times you can find the bites three in a row, right next to each other. They call it the breakfast, lunch and dinner. You want to have a good pest professional though, give you a quality inspection before you determine that you have bed bugs. Because of the wide variety of reactions you can't determin a problem just on the bites alone.