The traditional IRA contribution and the Roth conversion are separate transactions.
A Roth conversion performed in 2019 will be reportable on your 2019 tax return.
You'll only enter your traditional IRA contribution into 2018 TurboTax. TurboTax will prepare 2018 Form 8606 Part I to show the nondeductible contribution, with the amount on line 14 carrying forward to 2019 to be included on your 2019 Form 8606 line 2.
