Many start-up companies are founded by technical leaders - people with deep technical expertise in their field. Once the product(s) are ready to go to market, or perhaps only ready to engage with a beta customer, a new skill set is needed. This may be an opportune time to have an interim Vice President of Marketing. An interim Vice President of Marketing can be part-time, so you can access the marketing expertise needed without a large increase in your expenses.

Do not make the mistake of assuming that just because you have a good product it will simply sell itself. Most companies only get one chance to do it right. As they say, "You only get one chance to make a first impression." If you stumble on your first approach with a customer you will likely be hampered in all of your later approaches. Instead you need to build story and its supporting material - presentations, datasheets, pricing structure, competitive analysis, cost-benefit analysis, etc. Not every product will need every tool. But you do need to be properly prepared. That also goes for public relations and the press. You need to get your messaging correct.

Of course some companies may need an interim executive simply because the previous vice president left unexpectedly. By bringing in an interim executive you keep your business moving forward while you search for the right full time person to fill the role.