when income drops and before you being social security. Then you do large conversions up to a tax bracket threshold (12% typically). Roth conversions have a 5 year period for each conversion on the earnings portion. So for myself i plan on retiring at 61 and will do conversions each year until i decide to take social security. You still pay the taxes but at a lower marginal rate.

Another thing you want to do is open a Roth IRA now, since your first account needs to also have a 5 year period to satisfy the government and avoid penalties. You can just google "Roth 5 year periods explained". Some of the issues go away at 59.5 age, but its good to learn which and why.