Only what is necessary for him to demonstrate his intent. 

You can find plenty of forums online demonstrating their unhappiness.

It's what you can demonstrate as to your intent.  

It's going to be a little hard to demonstrated intent to hold when you already have a contract and your next property lined up. 

I over exaggerate but you get the drift.. if it was a prime property in CA or even here in Oregon and I was 300 a month neg I would hold but not in a market that does not demonstrate any real upward movement

Not only is there a lot wrong but many of the conditions demonstrate amaturish work and dangerous conditions. 

There is no specific holding period required other than you be able to demonstrate that you had the intent to hold for rental/investment should you be audited. 

There are several things you can do to demonstrate your intent.  

Your Business Plan not only needs to motivate you to success, but it needs to demonstrate to your partners and investors that you actually understand the market.  

There are many ways for the LLC to demonstrate that it is separate from an individual (tax ID, checking accounts, books and records, how documents are signed, separate credit cards, business address, etc).Note also that if you ask a corporate attorney about this you will get lots of different answers.