You bring up some great points, please look at the following I did and based on the IRS code section I believe it to be deductible. Now I would print this entire answer and put it in your tax file for your records should it be questions later.
The IRS FAQ and the IRS Publication 936, are using some of the same language however differing answers.
This is from the IRS Publication 2017, page 9 third column, https://www.irs.gov/pub/irs-pdf/p936.pdf
2. You build or improve your home and take
out the mortgage before the work is completed.
The home acquisition debt is limited
to the amount of the expenses incurred
within 24 months before the date of
the mortgage.
When this happens I like to look at the code, which is Internal Revenue Code 163.
"Section 163(h)(3)(B)(i) provides that acquisition indebtedness is any
indebtedness that is incurred in acquiring, constructing, or substantially improving a
qualified residence and is secured by the residence. However, § 163(h)(3)(B)(ii) limits
the amount of indebtedness treated as acquisition indebtedness to $1,000,000
($500,000 for a married individual filing separately). Accordingly, any indebtedness
described in § 163(h)(3)(B)(i) in excess of $1,000,000 is, by definition, not acquisition
indebtedness for purposes of § 163(h)(3). "
