Refinance after Seller Financing

[Jonathan Barnhill]

Newbie investor here trying to buy my first property with no money out of pocket. Just secured a $50K HELOC on my primary residence to use for down payment on a property that currently has stable tenants and will cash flow an estimated $500/month after PITI. Property price - $115K, 20% down ($23,000), seller offering financing for the remaining $92K at 5% (15 yr fixed).

My question: How long before I can refinance this property with a conventional lender at a lower rate in order to pull cash out for future investments?