the rule of thumb on operating expenses, for a hands-free operation, if the complex is older than 30 years, the expenses ratio is 60 (expenses)-40(operating income), if the complex was built within 20 years, 50-50, if within 10 years, 40-60, again this is varied by taxes and insurances, just a ballpark number.
now, this is before any mortgage payments, so if you planning to leverage 500k, your yearly outlay is 30k ish.
so this 8 unit barely breaks even, without reserves, your profit is the principal paydown.
but in long term, you are still gaining, as you can always increase rents, which translates into a better CAP = forced appreciation.