You can deduct costs that you actually paid in 2017. If you paid fees in 2018 you cannot claim them until 2018.
It usually does not matter because those costs along with other misc deductions have to be more then 2% of your AGI.
Disclaimer: Not a tax professional. Information gathered from internet links. Anything dated in June 2019 was posted in prior years and is before the 2019 limits and changes.
