Why you should do your homepage wireframe last: Seth absolutely nails this.
When building websites, I always recommend developing the home page last because the purpose of the homepage is to highlight content within the site. You need build out the site so you have something to highlight before you build the homepage.
The bottom line is that the home page is a window into, and an aggregation of – all the other content on the site. If don’t know what that content is, you’re going to have a tough time pulling together a wireframe for the home page.