I'm going to show off how horrible I am at math right now. It had not occurred to me to continue calculating ROI after purchase, although it makes a ton of sense. I tried to google the best formula to use and came up with NOI divided by total cash initially invested. Does that sound right?
So for my example, I purchased a property with $19,716 total in to make the deal happen. After a year and a half, the total cash I have made, minus actual expenses is $4,132.92. So if I am calculating correctly I am coming up with .2096, which is essentially a 21% ROI, right? So this is my actual ROI thus far for this property.
When I initially run my numbers, I account for putting money aside for vacancy, capex, maintenance, etc on a monthly basis, and my ROI looks like it will be much lower. For this one, I had calculated a 9.68% ROI when I purchased.
Would love some feedback on if I am doing this correctly. Thanks for the inspiration @Lance Robinson. I'm going to start tracking these numbers yearly as well.