Well mine seem to moult at different times (I have 40 of several different breeds) but as I understand it, there is not just one moult in a year: they have several partial moults where they just lose feathers from one area, then one big moult. My first chickens I have had for two years now and I have only noticed them do a complete moult once, just recently, but they have had partial moults before and their moulting schedule may have been messed up by being kept in a battery and then released to me. The different breeds I have seem to moult at different times but they have all done it now and some as early as August/September, but others as late as January so I think that when they were hatched may have a bearing on it too.