Set your own default reminder alert time in Outlook
If you're like me, you like to be prepared for your meetings. This can mean extra time for reviewing documents, brainstorming ideas, and printing handouts - not to mention travel time. If you're frequently late or unprepared for your appointments, simply change the default reminder.
Go into File, Options, Calendar and select the amount of time before an event that you wish to be reminded:
Of course, you can change the reminder time for a specific calendar entry or task when you create it or after the fact by opening it and choosing a new time setting: