For COR one does not need o pay any capital gain tax whereas selling will be hit with capital gain tax unless it is replace by another property with a 1031 exchange.

You 100% w/o question need to start the process. 

My intention is to buy a 2 o 3 bedrooms house and rent 1 or 2 rooms and after the 1st year, rent the whole house.

If you can't close before that the loan would get much more expensive o interest rates.

If the rehab is completed and verifiable, you should have no problem bypassing those seasoning requirements and completing your c/o refi. 

I needed a home, and because I was single w/o kids at the time I wanted to pursue property in the downtown Nashville area.

Reach out to me for some help if you want but all you would do is refinance as a N/O/O - Non-owner - Occupancy home/Rental going conventional or Non/QM. 

It's a 40 year fixed rate with the first 10 years of I/O, then it converts to a 30 year fully amortized loan. 

Bought in at $357k @ ~80% LTV, so $76k down put in $135k in repairs(construction loan), all of this bundled for a $423k I/O loan at 9.25%.Side note that may impact decision making: i am the GP of the deal and have 33% stake, deal is split three ways with other partners (33.3, 33.3, 33.3) Yes, i know this structure was not optimal for me personally, but it was my first deal and i had to make it happen.

Rates on properties like this can be around 6-7% without buy down, but some lenders even offer 5 or 10 year I/O options to help offset costs and get improvements and cash flows up before paying the fully amortized payments.Cheers!