details of primary home tax exclusion

[John Delk]

Hello,

I'd like to build a new home every two years and sell it, to take advantage of the capital gains tax exclusion.  

But what are the limits and tests I have to pass?  

I'd like to sell each home and repeat the process as quickly as the law allows.

Is two years defined as:  reported on two tax returns, or 24 months?

Does the two years "start" when I have a certificate of occupation and I move in, or does it start when I pull permits to build it?

Has anyone done this and have any lessons learned they'd like to share?

Thanks