Spell out months in text. In tables, figures, and references, abbreviate months with the first 3 letters.

In running text, write the date as Month DD, YYYY. Set the year off in commas only if it is used with both month and day.

We conducted a study in January 2003 on the prevalence…

We began a study on January 3, 2003, on the prevalence…

In tables and figures, avoid the constructions MM/DD/YYYY and DD/MM/YYYY (because usage is not consistent worldwide and they can be confused with each other). In references and in the body of tables, dates should be written as YYYY Mon DD (e.g., 2006 Sep 1).

Additional Information:

Formatting AM and PM
Using time abbreviations in tables, figures, Methods section