When you need a specific date for an important event, it can be helpful to have a few different words to use as synonyms for "fixes the date of." Some alternatives could include "determines the date of," "establishes the date of," or "sets the date for." Other options might include "pins down the date of," "finalizes the date of," or "confirms the date for." Whatever synonym you choose, it's important to make sure that your language is clear and precise so that everyone involved in the event knows exactly when it is happening.