Monograms are a very popular choice when it comes to choosing your wedding "logo." If you and your fianc have decided that you want to add your monogram on all of your wedding details there are some "rules" you should follow.
Etiquette dictates that you don't use your married initial until after you are actually married. That means you should not use your married initial on any wedding stationery guests will see before the ceremony, including your save-the-date card and invitation. Some people will use their married monogram during the ceremony because it symbolizes two people becoming one, so while some etiquette experts will say don't use your married monogram at all until after you've actually said "I do," I don't think the etiquette police will come after you.
Once you've tied the knot, you can use your married initial on any and every detail at your reception including your wedding favors, cake, menu cards, place and seating cards and any other items you are planning on having.
The invitation above is the Larson design from Abby Jean Press and is available in a rainbow of colors. The coral and white combination is shown here. You may be familiar with Abby, she's the author of the popular (and beautiful) wedding blog, Style Me Pretty.