Requirements for refinancing a SFH purchased all cash from HELOC

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I'm looking to purchase a few SFH investment properties. My primary residence is paid in full and I have a 300k Heloc open. I plan on purchasing a SFH in cash (Heloc), Cash out refinance, hold, repeat. My question is what specifically is required for this kind of refinance besides a little bit of equity? Is there a time limit- will I need to hold for a year and show the income on my taxes or is a lease on hand enough? Are smaller lenders more lenient with these types of transactions? Any specific information on this type of refinancing would be greatly appreciated!