How to convert primary residence into a rental?

[Will Koederitz]

So I am a little unclear on what is involved with converting a primary residence into a rental. I read often that people will buy properties using FHA or conventional as primary residences using low money down, then after the one year occupancy, purchase another and repeat. This applies to house-hacking as well. I am confused on how one continues to move forward because when I read the Fannie guidelines they say a primary residence can only be counted (the new rental income) if there is at least 30% equity. How can one move on to the next property if they are only putting low money down to start and then using it's income to qualify a year later? Maybe I'm misunderstanding something. I appreciate any clarification on this topic.