What age do chickens start to molt?

Mine start replacing first set of feathers by about 28 days post-hatch. They go through another set of feathers before reaching adult size which is completely replaced by first adult set by time birds almost full size (timing depends in part on breed). Thereafter feathers (all) replaced annually starting in late summer usually complete early winter. Some breeds go through annual molt faster. I do not know how the long-tailed birds go through feather replacement but i suspect it is very different for tail and saddle feathers.