House Hacking a 2-3 flat multi unit

[Joseph Tiralosi]

Hello! I am new to the forum and interested in house hacking a 2-3 flat multi unit in Chicago. Is it just considered a success early on if the unit(s) are “helping” pay part of the mortgage and my overall payments would be lower or is it only a good deal if the cash flow is equal to or exceeding the mortgage (excluding the unit I would live in)?

Thank you!