How do I avoid an underpayment penalty when I do a large ROTH conversion?

How do I avoid an underpayment penalty when I do a large ROTH conversion?

 

I plan on doing a ROTH conversion of around $80K.  The goal is to put my taxable income near the top of the 24% tax bracket for single filers. That will be $197,300.

 

I have never paid estimated payments before. I receive a paycheck and get a W2 at the end of the year. 

 

Last year I converted $70K and paid a $250 penalty.

 

I'd like to avoid that this year. Does it matter when during the year I do the ROTH conversion to avoid a penalty? 

 

Thanks