A common frustration in church leadership is "we announced it three times and people still didn't know" — usually because those three announcements were all in the same channel. Different generations and different people default to different channels entirely.
A layered approach covers more ground: a verbal announcement from the stage, a bulletin or program insert for those who read rather than listen, an email for the segment that checks it regularly, and a text or app notification for time-sensitive reminders.
Repetition across time matters as much as repetition across channels. A single announcement rarely sticks — plan to repeat key information across two or three consecutive weeks, with the urgency increasing as the date approaches.
Finally, keep a single source of truth for your calendar. When the website, the bulletin, and the verbal announcement all pull from the same calendar rather than being updated separately by different people, conflicting information mostly disappears on its own.