Since you filed the requisite statement waiving the carryback period, you need to carry the NOL forward to your 2017 return (amending would be needed, I presume) and then to 2018 (if not absorbed in the 2017 tax year).
Obviously, you need to calculate your NOL manually since TurboTax does not support that function and does not carry an NOL forward, for that matter. Subsequently, you can simply enter the NOL in the Less Common Business Situations section of TurboTax.
