If you choose to use TurboTax for the 2017 tax return then you will need to purchase, download and install on a personal computer one of the 2017 desktop editions from this website - https://turbotax.intuit.com/personal-taxes/past-years-products/
A 2017 tax return can only be printed and mailed, it cannot be e-filed.
You can file the 2018 return ...just use a zero for the 2017 AGI since you have not filed it yet.