Reminders for all-day events are sent at the interval you specify, counting back from the moment after 12:00 a.m. on the day the event occurs. For example:

Jeanna's Birthday is October 15th!

• You set a reminder to arrive 1 day before the event.
• The event technically starts at 12:00:01 a.m. on October 15th. So your reminder -- set to arrive 1 day before the event -- goes out at 12:01:01 a.m. October 14th.

Just think: now you've got all day to try and remember what Jeanna said she wanted for her birthday a few months ago. :o)