Relly Annett-Baker says the best web content is planned as early as possible so it can guide the design of the space it will occupy:
One of the most common web content mistakes is jamming too much into a space that has been defined by physical boundaries rather than planned out. If you manage it, the best you can hope for is that no-one notices it was a last-minute job. Mostly it reads like a bad game of Tetris with content sticking out all over the place.
