You should send save-the-date cards to all of your intended guests when either of these circumstances fit your situation. Even friends and family members who you already know will attend should be sent a card.
Although wedding save-the-date cards are not part of the etiquette for a wedding, it is wise to make use of them. It allows your guests to be able to set aside time for your wedding in advance. Generally, people would like to know about your wedding as soon as they can, especially if they are keen to attend. Also, if travel arrangements need to be made, then it is best to be informed early.
Save the date cards can take the form of any message medium, and often do. They sometimes correspond in style to the wedding invitations, or they take the form of refrigerator magnets, brochures, postcards, booklets, or tri-fold letters. The medium is up to you, but the shortness of the message usually lends itself well to magnets or small cards.
If you are going to use cards and stamps, you might consider creating your own stamp. You can make these stamps online and use your engagement picture. It’s fun and it makes it very personalized.
Who Needs them? If your guest list includes a number of out-of-towners, or if your wedding takes place during a holiday or other peak time, you are a prime candidate for save-the-dates. Since invitations don’t go out until 6-8 weeks before the big day, save-the-dates are the perfect way to give wedding guests a preliminary heads up so they can begin making travel arrangements. These days, however, more and more brides send these cards regardless of the time and location of their wedding. Why? Save-the-dates provide a fun opportunity to get the word out and foreshadow the style of your big event.