New Construction BRRRR

[Wyatt Harles]

I recently built a 3 bed 2.5 bath house that has an unfinished basement. My father and I are handy and have almost finished the basement, adding another bed, bath, and living space. I currently house hack the 2 finished rooms, and have another roomate renting the basement room in April. I will spend less than $5k for the project. The house cost $350k. I put $34k cash down, and got a 6% interest rate on the loan. The conservative value of similar houses with finished basement is low end $375k to high end $390k. Rents will nearly cover all mortgage plus utilities. When would it be reasonable to start thinking of refinancing/heloc to pull some cash out for next property? And is this method of buying new construction with unfinished basements to brrrr a good idea like I think or am I not accounting for something big?