All Marans go broody, but they are not your typical silky or game bird that will go broody 4 times a year. They have average level of broodiness. They will go broody when they will feel like. But there is no harm in trying, you can try inducing broodiness by leaving some fake eggs or golf balls in the best.
Our Cuckoo Marans became very broody at 12-18 months. I do not have anything against Marans but the ones we have are the last we will have. The ones we have are too broody, not all that personable, and do not have very good egg color.