For home made cloth masks, how often should they be washed with soap and hot water?

Varies: You have several options for optimal care of these masks. Twenty minutes in an oven at 140 F or a UV light will kill the viruses. Washing with soap & water on a regular basis will too. Understand that such masks do not protect you as much as they stop your breath/cough from casting out any virus/germ you may be carrying. The practice has been common in the orient for many decades.