You transfer the prior year tax data when you start the 2024 tax return.
See this TurboTax support FAQ for transfer prior year tax data to the online tax return - https://ttlc.intuit.com/turbotax-support/en-us/help-article/import-export-data-files/transfer-last-year-return-turbotax-online/L279eUvY2_US_en_US?uid=m6ayqk1s
You may have to clear the tax return and start over before you can transfer the 2023 tax data to the 2024 tax return -
If you have not paid for the online edition you are using, have not filed your tax return or registered the Free edition, then you can clear your return and start over. Click on Tax Tools on the left side of the program screen while working on the 2024 online tax return. Click on Clear & Start Over.