while it won't matter as the result will be the same (all interest is deductible), the intent is to take a 12 month average which would mean your 12 point average is well below $620,000.
For 2020, when that comes around suggest doing likewise but it could be your 12/31/19 mortgage balance already amortized below $750,000 and it won't matter. But if it does matter, use a 12 point average in 2020 as well!
