We just built our home this year. We started with a construction loan which, upon completion of the project, turned into a mortgage like any other. They did indeed run a credit check prior to starting, so as far as credit scores are concerned, you want a good one to buy OR build.
In addition, I'd recommend looking online at floor plans and exteriors, and bringing those plans to builders to see what they can do for you and for how much. As with anything, the more ornate you make your home (even in terms of hip roofs or extra peaks), the more $ it'll be.
Oh, timeline: broke ground late last October, moved in April 30. My husband did a lot of electrical/plumbing work himself though, so it probably wouldn't have taken as long if we'd used sub-contractors for everything. Hope that helps, and good luck!