When does one pay taxes when converting IRA to a ROTH IRA?

I am considering converting my small IRA into a ROTH IRA. Can I do that in the middle of the year and report it on line 15b as a taxable distribution and then pay the taxes for the year I am converting it in? 

The IRA is a residual converted amount from a company 401k done a few years back.

My income is such that I may be able to cover the taxes owed for 2017.