I have reference material of the "3" days "3" nights but it refers to scripture. Which I assume you have. used in 1st century material other than the bible?
I only have material referring to why when "x" days and "x" nights is used it is not an idiom and gives biblical references. My material attempts to explain when it is "factual" or when it is "idiom". But, my material talks Bible . Also my reference material refers to other reference materials.I have no Idea as to the century. Title "THE THREE DAYS AND THREE NIGHT OF MATT.12.40" all biblical I do not know about 1st century usage.
To argue a point may be fruitless.6th day people may want to stay 6th day people.