The invitation to your event is one of the most important aspects of the entire planning process. You don’t want to send out the first invite too early or too late. Three weeks out is a good rule to live by. But if you want to get on executives’ calendars, you might want to send it out even earlier. A more detailed, elaborate invite for a dinner event is appropriate, but you may want to be more simple and straight to the point if you’re presenting a demo. Include directions that include access to public transportation.
Source: eloqua.com