Conventional loan approval/HELOC strategy help

[Max M.]

I currently own my home outright and am evaluating the best course to take for purchasing buy and hold rental properties. I have no outstanding debt except for a 300$/month car payment. Currently one income source around 50k/yr. I am worried about getting approved for conventional loans on multiple properties considering I do not have 2 years of landlord income. Will getting a HELOC for a house owned outright (let's say...300k+) be enough/improve chance to get approved for multiple conventional investment property loans on 1 income? Or, am I better off selling my primary (looking to move soon so either primary gets sold or rented) and having cash on hand to buy properties and then refinance immediately. I'm nervous about doing that as I don't know how likely I would get approved for 20% down on multiple properties without a 2 year history and how DTI will factor in before this is counted.

End goal is to 20% down on a few different properties and have them rented to pay off mortgage/HELOC (if necessary) and build cashflow over time.

Hope this makes sense!