Online TurboTax can only prepare a 2018 return. To prepare a 2017 return, you would need to purchase 2017 desktop software.
https://turbotax.intuit.com/personal-taxes/past-years-products/
The 2017 return cannot be efiled. It has to be printed, signed, dated, and mailed.
If you efile the 2018 return, it will ask you for the 2017 AGI for verification. Since you did not file a 2017 return before November 2018, you would use a 2017 AGI of 0.
