However, there is no specific holding period contained in the tax code or regulations and there is no "safe harbor." 

Make sure the location is safe first.  1.  

Maryland has more likely (but still long shot) criteria.But, it is not safe to assume you won't be sued since the US has about 30 million civil lawsuits pending as I type this.And, it is against public policy to insure intentional torts.

Quote from @Zachary Deal: Choose neutral safe tones and get nice materials but don't splurge too much on very fancy cabinets, counters, appliances that someone else may not value the same as you.This is so true.

Break evens under 4 yrs are generally a safe bet, but I prefer between 2 and 3 years.

Your not correct under many different circumstances.First property tax is 1.1% (fairly safe) with 2% annual increase (prop 13).Next expenses include a lot more than property tax and interest. 

Louisville is fantastic for cash flow and is a safe place to start since we don't typically get caught up in the roller coaster effect of steep appreciation followed by sudden pull backs when the market isn't red hot.  

While your deposit remains safe as equity. 

However, it's a safe bet that these respective areas will continue to appreciate steadily for the reasons noted.

The six month cd isn’t the point my understanding is that I can’t just take out the HELOC, I need to actually use the money for my plan to work and a short term CD seemed safe and reasonable