When referring to a set or established date, there are several synonyms that can be used in place of the phrase "fixed date of." These include terms such as established date, designated date, appointed date, prearranged date, scheduled date, arranged date, and set date. Depending on the context and intended tone, each of these synonyms can convey a slightly different nuance, but all serve to indicate that a specific date has been determined or agreed upon in advance. Whether used in a business context or simply to discuss social plans, these synonyms can help to vary and add interest to our language.