While hiring an agency to make the official website for your startup, the question arises on the order of priorities of events, whether content or design. Sure, if you're a technology guy with advance knowledge of coding, programming or web designing then you'd be working the build yourself, but not many entrepreneurs have the luxury of that knowledge. Either way, the options in designing are almost unlimited today - from swirly animations, smooth java, imbedded flash plug-ins and parallax scrolling, the use of white space making everything seem smarter and customized fonts and shades - among other magic that gives your website the wow factor.

Design is expensive
If you start off with designing without content in your hand, you can end up costing a fortune because it will be vast and artistic, not catered to your jest or target audience as such.

Content will be haphazard with the design already in hand
So many designing software's, agencies and designers themselves will jump the wagon in selecting a template or a pattern for you right at the beginning.
Key Takeaway from this:

It's best if content takes the head start because spinning the design based on the content with be easier, and more appealing. When content takes the lead, it lays the foundation for a more cohesive and meaningful design. By having a clear understanding of the content's purpose, tone, and structure, designers can create visuals that complement and enhance the message, rather than trying to force-fit content into a pre-existing design template.