Roth conversions are made in a particular year, not for a particular year.
The Roth conversion performed in January 2016 is reportable on your 2016 tax return, not your 2015 tax return. If you reported the Roth conversion on your 2015 tax return, you'll need to amend your 2015 tax return to remove that. You'll still report the nondeductible traditional IRA contribution for 2015 on your 2015 tax return.
The January 2016 Roth conversion and the traditional IRA contribution that you plan to make for 2016 must be reported on your 2016 tax return. Any Roth conversion you perform in 2017 must be reported on your 2017 tax return.
