Marketing starts with day -1 of your startup and it never ends. In a small company, marketing goes together with any out-of-the-building activity you carry out: a presentation, a demo event, an investors forum, a provider search, an interview to recruit talent, etc. The objective is not to close sales, but rather the positioning of your company/product inside potential clients mind. You are not interested in everyone, but rather just in those innovators that are eager to use what you are building. Others will come afterwards. And they are willing to generate a conversation with you, they are really curious about what you are doing, so they want you to pay attention to them. Don’t disappoint them. Make them trust you. And them move forward.