ASAP. I started a year in advanced right after we got engaged. But I was doing my interent searches and window shopping like 6 months before that so that when it came time to make appts with vendors I already had lists of people to call. I think you could do it in 7 months if you find the perfect vendor on your first try for most of them. Also if you are using vendors who do everything then you would need less time too because the less people you have to interview the better.
Good Luck