Anyone know the ASCII code for infinity?
But seriously it depends on a lot of factors. 10,000 square feet of office space will lease up faster than 100,000 square feet. I would expect a project to take a anywhere from 6 to 36 months. If it's much longer than that it's probably a sign that there's insufficient demand to justify building new office space.
One way to look at it is to determine the net absorption in your market or submarket. This will generally come from a third-party source like CoStar, or market reports from commercial real estate companies like CBRE, Colliers, Cushman & Wakefield, etc. Lets say your submarket contains 1 million square feet of comparable space (say Class B), average occupancy is 90%, and net absorption was 50,000 square feet last year (and is expected to be about the same going forward). If you built a new 50,000 square foot office building the submarket would now contain 1.05 million square feet. Your office building would represent 4.76% of the market. As new space it might be expected to capture a larger portion of the market, say 8%. So 8% of 50,000 is 4,000 square feet. Obviously that's not very much and at that rate lease-up would take a decade or more.
