Mortgage interest tax exempt

Hi,

I have purchased our 2nd home in July, 2023 in SC ( mortgage payment starting from September )
with 1st home being in NC both having mortgages. The mortgage interest on the SC home is higher.
Filing status - Married Filing Jointly.
I am planning to file for legal residence for the home in SC in December for 2 reasons -
1. The mortgage rate provided for the SC home was considering it would be our primary home.
2. Lower property taxes - the special assessment ratio is 4% instead of 6%.
Given the above situation, how does the math work for tax exemption on mortgage interest towards itemization?

1. Mortgage interest is tax exempt for NC home from Jan to Aug (when it was primary) and SC home from Sep to Dec?
OR
2. Mortgage interest is tax exempt for NC home from Jan to Nov and SC home from Dec only (as that is when I will file for legal residence though I closed in July)?
OR
3. Mortgage interest is tax exempt for just for SC home from Sep to Dec?
OR
4. Mortgage interest is tax exempt for just for SC home from Dec (as that is when I will file for legal residence though I closed in July)?
OR
5. Any other scenario which I did not even consider above?

I will be sure to work with a tax consultant but any expert help ( need not be professional ) does help.

Thanks in advance