Retirement tax questions

Thanks for the reply.  I am also planning on doing a Roth conversion in January of next year.  Is it acceptable to pay the tax on the conversion from withholdings from a monthly pension spread over the entire year rather than doing estimated quarterly payments?  If done by quarterly estimated payments, can the tax bill be spread over all quarters from the conversion or must the entire tax bill be paid in the quarter of the conversion.  Are the rules for withholdings different, i.e., can the taxes from withholdings for the conversion could be left to later in the year, even if the conversion was made a the beginning?