Open Plans and choose Plan an event. Give it a name, add the details and a place if useful, then either set the date or offer dates for your folk to vote on. Starting an event or date poll needs Plus, Together or an active Plus trial.
While a date poll is open, the organiser can add or cancel choices, keeping between two and ten available dates. Cancelled choices stay visible as cancelled. Once you have a date, confirm it so people can answer the invitation.
People can respond to the event and include the extra details offered on its page, such as a message or extra guests. Add lists and notes for the practical things. Use Add to calendar to save the plan to your own calendar.
After an event has passed, its details and attendance answers are fixed, but you can still add moments from the day.