THE LONDON CHRONICLE, England, Oct. 7, 1773  An extraordinary issue, as page 5 contains what might be the first periodical publication of one of Phillis Wheatley's poems, "On Imagination".
Wheatley was an American writer considered the first African-American author of a published book of poetry. Born in West Africa, she was kidnapped and subsequently sold into slavery at the age of 7 or 8 and transported to North America, where she was bought by the Wheatley family of Boston. After she learned to read and write, they encouraged her poetry when they saw her talent.

We can find no information noting this poem was printed earlier in any publication.
Other nice content on page 6, including a report headed: "America" from Newport, and a letter from Pittsburg beginning: "The Design of establishing a new government on the Ohio has excited a very alarming jealousy amongst the Western Indians...". More as well, including mention of the rebellion of slaves in Honduras.