The real Form 1099-R will be a 2023 Form 1099-R with codes J an P and is the proper way to prepare the dummy 1099-R entry in TurboTax. This has the same effect as a 2022 Form 1099-R with codes 8 and J except in the application of any tax withholding. When you enter a Form 1099-R that has code P, TurboTax asks you to provide the year of the form, so you'll answer that it's a 2023 Form 1099-R. Your "dummy" Form 1099-R should be identical to the actual Form 1099-R (to the extent possible), simply entered before you receive it.
Box 3 does not apply to any distribution from any kind of IRA. Leave it blank.
