I am starting a Joint Venture BRRRR with a family member in the San Diego area.

However, you can certainly improve your chances at success by focusing on areas that may be better than others. 

The dissent agreed with the majority that the sale must include a permanent dwelling and that a principal-residence sale must include a home and improvements, but argued that the dwelling could be demolished and rebuilt as the petitioners had done, where even though the original house was gone, this would be defined as renovation of the original principal residence, not as a different residence, and not interrupt the 5-year period. 

From there, you'll know if you need to save more cash, improve credit score, or if you're ready to go. 

Assuming you put down 20% your looking at around around a $300k raise which is a good starting point for partnerships and joint ventures. 

The dissent agreed with the majority that the sale must include a permanent dwelling and that a principal-residence sale must include a home and improvements, but argued that the dwelling could be demolished and rebuilt as the petitioners had done, where even though the original house was gone, this would be defined as renovation of the original principal residence, not as a different residence, and not interrupt the 5-year period.

Gradually improving the property by raising rents, improving curb appeal (trimming overgrown trees/ bushes, new landscaping, power washing).

It’s what you actually paid for it, along with any major improvements. 

When buying a property and the exit is to refinance over and over, what is the best balance to have when it comes to cashflow and using the NOI to improve the property to grab more money at the refinance ?

I should be able to help you identify what to look for, and how building an ADU really improves the numbers on a property.