You can't amend just yet, but here are the instructions for when the option is available:
1. Sign in to your Turbo Tax account.
2. Scroll down to Your tax return & documents, click Show on the right.
3. Select 2019 and then click Amend (change) return.
4. Carefully follow the instructions. Don't worry if your refund changes to $0. This is normal on amended returns. If you will get more money back by amending, the refund box will show you the amount.
5. When finished, follow the instructions for printing and mailing your amended return as amendments can't be e-filed.
You won't see the option to amend in Turbo Tax until after February 5. If you haven't received your refund by that date, you should wait until you get your original refund.
It looks like the date for 1040X printing has been moved back to 2/12/2020.
https://care-cdn.prodsupportsite.a.intuit.com/forms-availability/turbotax_fed_online_individual.html