If you made a Roth conversion in 2019, The 1099R from your t-IRA will issue next year and it will be reported as a taxable distribution for tax year 2019. If the t-IRA contribution was made in tax year 2018 (even if made this year) you need to indicate on your 2018 return if it was deductible or after tax. If the latter, you need to put it in on 8606 so when you report the 2019 Roth conversion, the 1099R distribution from your t-IRA will be considered non-taxable. My general recommendation is to make the non-deductible t-IRA contribution and the subsequent Roth conversion both in the same year and, preferably, early in the year. It makes the tax handling more straightforward so that all the paperwork lines up.
