It's a common misconception that web accessibility can be ignored until development is almost complete, and then we can ask the developer to step in and fix all of the accessibility issues.
This is completely wrong. Accessible design starts in the design phase with the experience designer, and the specifications for the user experience that are documented in wireframes and visual design style guides. If accessibility is considered at these stages and documented for the developer, about 75% of the accessibility issues we typically see would not exist, and experiences would be designed in a way so that that they made sense for keyboard users.
Please see my Slideshare presentation to read more.