Nope...you can only enter and save 2020 data into the actual 2020 tax software...when it actually comes out.
"Online" 2020 software expected sometime in December.
"Desktop" 2020 software expected sometime in November.
In both cases, the early software will only be marginally correct, and require significant software updates thru Jan of 2021.....or even Feb/March for more complex situations.
The Desktop 2019 software would allow you to use 2020 data in a separate new test tax file, but it would use 2019 tax rules....would be close enough, but wouldn't include the "stimulus" part that will be in 2020 software...and you could not transfer the actual data to the 2020 software when it comes out..
.....or....the 2019 Desktop software also has a "What-If" worksheet that uses your 2019 tax data...and projects the same values to 2020...and also allows you to change the 2019 values on that worksheet if some are expected to be significantly different for 2020...but again, none of the actual values you enter will transfer to the 2020 software as 2020 data.
If you used the "Online" 2019 software...you must never test or enter the next year's data in your Online file until the proper year's software is enabled......messing in your 2019 Online tax file now would irretrievably destroy your 2019 tax file and it's data. If you created an entirely new & separate Online account, you could have perhaps messed in that earlier this year, but again, the data would remain as 2019 data, and I think you can no longer create new 2019 accounts anyhow...and it all shuts down by the end of October
The 2020 program doesn't come out until November and Turbotax is not set up to allow partial entry during the year. If you have a business, you can track your PNL with Quickbooks and then import your information into Turbotax, but that's about it.
You can estimate your 2020 taxes by creating a dummy return with the 2019 program, or by using the Taxcaster, or the IRS tax estimator.
If you're planning a distribution from your 401k and it is not COVID related, take 22% of the amount and that's pretty much the tax you can expect to pay. if you are not yet 59 1/2 years of age, add 10% penalty tax.
If you're in the 25% bracket use 25% instead of 22%.
Fancy software is not needed.