Correct usage of preposition "of" with month and year only

I've been researching like crazy a definitive source for determining whether I can correctly and properly use the preposition "of" to write the month and year only.

I located one source, the Office of Marketing, from Western Michigan University, which clearly states, 'Do not use the word "of" between the month and the year.' However, it lists no source for that statement. See: https://wmich.edu/writing/rules/dates

In 2017, a user asked a similar question to mine here in English Stack Exchange. In late October 2017, user Ringo left a single comment that made me believe the use of the word "of" between the month and the year is acceptable and is considered formal language.

Here is Ringo's response: "If it needs to be formal/official, then say 23rd of July, 2017. If it's less formal, then 23rd July 2017 is probably fine, because it's clear and sensible for the reader. – Ringo Oct 19 '17 at 4:43"

However, Ringo replied using a specific day of the month along with the year. See the original question and answer here: https://ell.stackexchange.com/questions/145118/using-prepositions-with-date-and-time

In 2013, a different user asked a question here on English Stack Exchange about peoples' tendencies to omit "of," which strikes me as a stylistic PREFERENCE as opposed to a grammar RULE. Please see the original here: Is it common to omit a preposition (in / on / of) before “the month (year / week /day) when they are used adjectively and adverbially?

I am writing a nonfiction book in which the month and year only (no specific day of the month) is prevalent and essential for telling my story. I wrote everything consistently as "March of 2019, March of 2020, etc.".

I feel incredibly stuck not knowing the rule as to whether I am writing improperly by including "of" between the month and year. Appreciate your insight and guidance on this.

Solution 1:

Ringo is wrongo - this depends on the editing style that controls your publication.

Chicago Manual of Style 16th, §6.45: In the month-day-year style of dates, commas must be used to set off the year. In the day-month-year system — useful in material that requires many full dates (and standard in British English) — no commas are needed. Where a month and year are only are given, or a specific day (such as a holiday) with a year, neither system uses a comma. CMoS uses ”23 July 2017” and "March 2020.” (Per §9.32, the cardinal number of the date may be pronounced as an ordinal that is, "twenty-third.")