Private Money Amortization

[Elliott Bingham]

Good morning BP community!  Quick question for an aspiring investor.  

How long do you amortize private money? Looking at a LOC from a family friend and trying to figure out how to approach the interest part of the equation. I'm wanting to amortize the outstanding loan balance, but over how many years? Is there a good formula for keeping up with the outstanding balance when making draws rather than taking a lump sum out at one time? Any advice would be appreciated!