When I write a wedding-date scene I treat the date like a secret that needs the perfect unwrapping. I like to start by deciding who announces it in-world — a delighted parent, a nervous best friend, a smug officiant, or even a passive-aggressive subreddit post — because that choice sets the whole tone. If the wedding matters to the plot, make the reveal carry subtext: a month like 'June' can feel bright and hopeful; an off-season date like 'November 3rd' can whisper of compromise or urgency.
Show reactions before you lay down the numbers. Let someone choke on tea, let the florist stare at a calendar, let the protagonist hear the date repeated in a voice that cracks. Small sensory details — the scratch of a fountain pen on an invitation, the crinkled envelope, the smell of old paper — make the date feel lived-in. Save a little specificity for later; sometimes withholding the year creates suspense, other times the exact day (5/12 vs. 12/5) can be used for cultural flavor.
Finally, tell your readers clearly in the summary or tags if the date matters for timeline reasons. I always include a brief note like 'wedding date revealed in chapter 12' so people who care about ages, timelines, or canon continuity aren’t left squinting at the calendar.