MDC Brooklyn Handbook page 36, point 4 states he shall be given access to regular showers. Barring security concerns (eg Solitary, or low staffing) that would mean at least 1x a day. However in practice inmates can be restricted to 1x a week before any 8th Amendment “cruel and unusual punishment” concerns start cropping up. So to answer your shitty ask, 31 days in the months that have 31 days.
As noted above that less than once a week tends to rise to cruel and unusual punishment. Given the ~ 4 weeks that occur in 31 days, it would be 26 to 27 days to lose.