When is the right time for usability testing?

Doing user testing for a web site design and development project

So the issue is this:  you know that you need to complete user testing on your designs in order to have a successful site or product, but you also have to maintain control over your branding and your message.  How do you structure your process so that you are successful on both fronts?

I'm going to start sounding like a broken record here, but as always, the answer is "it depends."

The Apple Example
While there is no doubt a quality control and testing process within Apple, we all know from stories both true and exaggerated, that products like the iPhone, etc. are NOT sent out to focus groups all around the world for feedback. 

The Drupal.org Example
On the opposite end of the spectrum, we have the Drupal.org redesign, which is looking like one of the largest (if not the largest) democratic website design projects ever conceived.  All are welcome to participate in the new home for one of the most popular Open Source Content Management System platforms available.

A more common scenario
More typically, you will have both a smaller base that will give feedback and a slightly less strict process for allowing alterations for the original design.

When and where you put user testing in your process will absolutely have an effect on your end product.  Approving an initial aesthetic and information architecture FIRST before opening it up to user feedback will make sure that your users are really only commenting about functionality and interaction.  Or, to be more specific, some of their comments about aesthetics will most likely be looked over and only passed on if there is a unified voice. 

Keeping the process completely open from the beginning will give you a different product.  It will be shaped much more by users than one that has built in constraints. 

The strategic question, from my perspective, is this:  what DO you want to give your users/audience control over changing, and what is so central to your brand/product that you are not willing to compromise.

After you decide the answer to that question, the order of things should be much more simple.