Prepositions related to the festive season

Hi! Another common error from our Skype English classes is that which concerns the prepositions of time for this time of year. For example, we say 'at Christmas' and 'on Christmas day/eve' and 'on new year's day/eve'. The day of 'reyes magos' is called 'epiphany' or 'twelth night' and is not a holiday in the UK or the US. The preposition 'on' would be used in these last 2 examples. Hope that helps and Merry Christmas.