After you file

You'll need to amend your 2016 first, using your 2016 amended numbers.  You can look at 2017 and then carry it over to 2018.

To input your amended 2016 return:

https://turbotax.intuit.com/personal-taxes/past-years-products/

To carry over your amended 2016 return into 2017:

2017 Turbo Tax