I deployed to Kuwait from 08/20/2019 to 07/20/2020 but I cannot enter any dates prior to 2020?

For your 2020 tax return only enter the dates you were deployed in 2020. Therefore, you will enter 1/1/2020 till 7/20/2020.

Please be aware if you received nontaxable combat pay (Q code in box 12 on your W-2) then you have the option to include or not included it to calculate the the Earned Income Credit (if you qualify).

1. Login to your TurboTax Account 
2. Click on the Search box on the top and type "EIC"
3. Click on “Jump to EIC”
4. Continue "Do you want to include your combat pay in your income?"  and select "Yes" and "Continue", write down your EIC and refund
5. Click "Back" and select "No" and then click "Continue".
6. Compare new EIC and refund with written down amounts.

Please see What are the qualifications for the Earned Income Credit? for additional information.