How do I calculate the average mortgage balance on property that I converted from a rental to my primary residence? I rented out this property for the first 8 months of 2020, then lived there for 4 month after that.  Same mortgage loan all year.  Want to see if I am over the $750,000 limit.

I found a worksheet in Publication 936, page 13.  The first box says "Enter the balance as of the first day of the year that the mortgage was secured by your qualified home during the year (generally, January 1)".  I'm thinking I would enter the balance of the mortgage when the property became my qualified home when I moved in, not from the beginning of the year when it was a rental.  Trying to determine if TurboTax calculated properly.