Are you asking this in regards to holding periods for capital gains tax calculations ST vs LT?

Is the holding period calculated from the purchase date to the sale date?

If you run the numbers properly, you’ll see that borrowing money, even hard money, is almost always cheaper than giving away half your profit.We use the calculation above for screening, but we always run the numbers in detail before agreeing to a loan.

Calculate operating expenses, including property management fees, maintenance, taxes, insurance, and utilities.

Check it against the information that you have, if it doesn't match, make your own calculation.  

The biggest drawback I am having is calculating cost for repairs & finding a reputable contractor for a fair price - I know nothing about renovations right now.  

The COC on the 1st house if I am calculating it right would be just shy of 10%.  

- Total 6 yrs  i.e 4 yrs (75% was rental and 25% primary) + 2yrs (100% primary)- $300k capital gain / 6yrs is the net gain per yr - $200K for 4 rental yrs + $100k for 2 primary yrs- So $150k (75% of $200k) is taxable and the remaining $50K (i.e 25 % primary) + $100K (2 yrs 100% primary) i.e $150k in total will be tax-free? 

You calculated $400/month, but did you account for repairs and vacancies?

Here's a bit more in detail about how rates are calculated for DSCR loans:1.