Numerals
Traditionally, numerals were used exclusively for street addresses and were omitted in all other instances, including the date and year.
Today’s invitations are much more creative with the use of numbers. Often the date and year are displayed in decorative numbers that add to the appeal of the design.
Abbreviations
Traditionally, abbreviations on invitations were not used, including abbreviations of times, like “PM” instead of “in the evening.”
Today, rules are much less formal. Months, days of the week, titles, and addresses are often abbreviated. The use of abbreviations is entirely up to you.