Mark,
Speaking just of construction time, and using "Big Time" Contractors like I usually do, I find construction to be 7-9 months on my typical project.
You have to consider "working months" as Tom said, so in Minnesota (where they can work May until October we had a fall start, with only a month of clearing, all of the next summer (six months) and then a few months to finish the next summer (May until the last plant date of August 15) or about 11 actual working months, spread over almost 22 months of construction time.
In the south, we time the projects to a June1 planting start (it takes about six weeks, or until July 15) and start construction in October, figuring that we will lose a month or two in the winter to rains. Some of it depends on what phase construction is - if clearing and earthmoving are done by winter rains, sometimes irrigation and drainage can continue, albeit at reduced pace, throughout the winter, reducing "lost time."
A few things have always amazed me about golf construction -
How much work the big boys get done with about a dozen people in the shaping and irrigation phase (by planting there are dozens more folks working to finish the course) and how much faster they have gotten.
How much hand work is required to finish a course of 160 Acres or so.
How the 80-20 rule applies (as it does when we are getting plans out) - We think we are almost done, and the last 20% seems to drag on much more than it should. I guess the primary reason is that rain requires total redo of finish work.