Pro-rata formula question for doing Traditional IRAs to ROTH conversion please

I have one IRA account with deductible and other one is non-deductible.

If I do the some of the amount to ROTH conversion this month(November)

for this year, will I be using  calculations for "pro-rata" November conversion

amount, OR end of this year amount in the converted amount(ROTH account)?

 

Read that all Traditional IRAs account amounts used from the end of the year

amounts for sum year end value as part of the formula.

Thanks!