Correct. The Roth conversion that you do in 2023 will be reportable on your 2023 tax return.
The pro-rata rule will apply to your 2023 Roth conversion, performed on your 2023 Form 8606 (and likely Worksheet 1-1 from IRS Pub 590-B). If you have no funds in a traditional IRA at the end of 2023, all of your basis will be applied to your 2023 Roth conversion and, if the amount of your Roth conversion is equal to your basis, the pro-rata calculation will result in 100% of the conversion being nontaxable.
