Before picking a slot, show percentage of other's response selection.
Let event respondents see, for a given available timeslot, the percentage of attendees that have picked a specific time.
Example. If 3 time selections are available, show that 50% of answer (thus far) have picked option 2 versus 10% for options 1 or 3. Goal is to nudge late responses NOT to derail the natural coalescence around a slot and nudge them to consider one slot option more than another. This helps meeting organizers to not have to go to square 1 late in the game.