Pick the beans when they barely start to turn yellow.
Curing is a process of fermenting combined with drying. The beans are often immersed in very hot water for a minute or two or left in the sun in plastic to heat up. Then they are wrapped up in a towel, put in a box to sweat, then after a day or two put in the sun to dry a bit. Back and forth from the box to the sun for about 3weeks.
It’s very hard to know, without experience, whether at any given time the beans need more sun or more sweating. Too much sun they dry out. Too much sweating they get mold. Suerte!
Peter