Monograms have changed a lot in the last fifty years.  The large, central letter is supposed to be the surname (family name), but the trend toward equal-sized letters has led many to put them in normal order. For Jane Ann Doe, the traditional would be J D(big)A, but the modern, equal-size, would be JAD.  The customer probably has a preference, but if not, monogram etiquette is surely available online.