The days of personal use is for days "AFTER" you converted the property or space to a rental. Most likely, that will be ZERO.
What you used the property or space for while it was *NOT* classified as a rental *do* *not* count for anything.
If you converted the property or space to rental on Dec 12 and it remained classified as such through the end of the tax year, then you have 19 days the property or space was classified as a rental. The total number of rental days/business use days, plus the number of personal use days can not exceed 19 in this particular example.
