15K First Deal- how to make a steal of a deal?

[Abigail Ellison]

hey there community- I found an owner offer for a 15K fixer upper on a double lot in a small town.  There is some flexibility here but want to do it the best way possible given it's my first deal! Any ideas on best structure would be so helpful as I am a talented creative and learner financier.

Holding costs are $220/month. ARV in the $55K range conservatively. I would like to do the BRRRR method ( double check my rrrrs.... ). Owner is willing to finance with a downpayment of 4K and no interest.

I have a line of credit to draw on at 4.5% for interest only and 5.5% for a mortgage set up.  Was thinking the best way forward is to do the downpayment and repairs, holding costs and monthly payment for 2 months from the line of credit roughly $11K and then RENT for $650/month and then REFINANCE and of course repeat.

Is this sound thinking?  

Many thanks in advance!  abigail