Depends on the complexity of the website.
If you're building a Single Page Application (SPA) or just a static, only a couple page, website then just get on with it.
However, if you're building something like facebook. Not social media platform, but just the multitude of components and moving parts that are there. Then it would be better to come up with a shared idea in the heads of the dev team and then work on a couple of use cases with the Minimum Viable Product (MVP) outlined, e.g. specific features etc. After that i'd throw together a couple of wireframes to confirm what it would look like then start building it - i.e. actually begin to code it.
Once you begin coding it's more of an iterative process as things will change, they always do. It doesn't mean you have to do everything all over again that I mentioned above but rather just acknowledge the new changes and their impact on complexity/time frames etc.
When you do finally start to code, try and have a rough timeline when features will be completed. Then just work off "sprints" or the "Agile" approach to development.
Hope this helped :)