When it comes to invitations, it seems anything goes, but there are still some rules that should be followed.
To write the time of day, it is recommended to write the time followed by a.m. or p.m. in lower case with a period after each letter, such as 12:30 p.m. There should always be a space between a.m. or p.m. and the time.
The “a.m.” means Ante Meridiem - before noon – and “p.m.” means Post Meridiem - after noon. Although you will find some books that tell you to capitalize the A.M. or P.M., doing so on an invitation is usually too overpowering to the rest of your text. When it comes to writing “noon” – 12:00 p.m., or “midnight” – 12:00 a.m., you can use “twelve noon” or “twelve midnight.”
On formal invitations, dates and times are always spelled out:
Saturday, the first of April
- using “on” before the date is optional, but do not capitalize the “o”
- do not capitalize the date, “first”
at six o’clock
- using “at” before the date is optional, do not capitalize the “a” or any other letters
- adding phrases for time of day is optional, but no letters are capitalized
“in the evening” applies to 6:00 p.m. and after
“in the afternoon” applies to after noon and before 6:00 p.m.
“in the morning” applies to after midnight and before noon
Two thousand and fourteen
- the listing of the year is optional
- only the first letter of the first word is capitalized as in the “Two” of the year