Wait until you are married before you break out the stationery monogrammed with your married initials. Fold-over note cards are fine to use for shower thank yous. You can use your monogrammed maiden-name stationery, too.
There is no single stationery required for thank-you notes, although you’ll probably use a standard one-sided or single-fold note card and matching envelope. The paper can be plain or bordered, white, ivory, ecru or a pastel color. Use ink that is easy to read; black ink is always legible.
A bride signs with her maiden name (or pre-marriage name, if an encore bride) before the wedding, and signs her married name afterward. When using monogrammed stationery, the notes
sent by the bride before the wedding have her maiden name initials; post-wedding notes have her married initials or the couple’s last-name initial.
Grooms can write thank-you notes, too! When husbands and wives share monogrammed stationery, the last/married name initial, hyphenated initials, or double last-name initials (when the wife keeps her maiden name) are used.