Save the date invitations are the precursors to the invitations themselves. Consider save the date invitations as an alert to your guest. They let them know that they should keep a date on their calendar free, as there will be a special event to attend. Save the date invitations include only the crucial information about an event: what it is (this can be vague, but be sure to distinguish between a wedding and a party!), when it is, and where it will be held.
Save the date invitations should include the necessary information that your guests will need to plan their day, and possibly the days leading up to that day, accordingly. Your guests will need to know what type of event is being held. Is it a wedding? A birthday party? A baby shower? Be sure to specify, so that your guest can begin to plan their outfit, and what type of gift they might purchase. Next, specify the date. Be sure to include both the day (Monday, Tuesday, etc.) and the date. Also include the time -- when the event begins, and when it will end. If you don't know when the event will end, simply put [begin time] - . Finally, include the location. While you don't have to specify the exactly address (save this for the actual invitations!), you should put the city and state. This also helps the recipients of your save the date invitations to plan their travel arrangements accordingly.
Save the date invitations can be worded formally or informally. The choice is yours. If you are planning a wedding, try and word your save the date invitations in accordance with how your wedding invitations will be worded. So if your wedding invitations are very traditional, word your save the date invitations likewise. Also, be brief and to the point. You can add extra information in your invitations. For now, your save the date invitations are accomplishing only one thing: ensuring a clear calendar date for your event!
Your save the date invitations should be mailed at least six months in advance of your special event. If you are sending save the date invitations to guests who may have to make extensive travel arrangements to attend, you should consider sending them their save the date invitations a year in advance.