For boosts that apply to all users or a user group, events fire at 10:00 UTC the day before the boost’s UTC start time. This
is because boosts are relative to each user’s time zone, and the start event must fire before users in the most advanced time zones would see the boost.For user-specific boosts (boosts that only apply to one user), events fire at the exact boost start time in that user’s time zone.Make sure to take into account users’ time zones if scheduling notifications from this webhook event.