Pitman's own Phonotypic Journal documents the English Phonotypic Alphabet's completion in June 1845 and its foreign-language extension in July 1845

isaac-pitmanalexander-john-ellisenglish-phonotypic-alphabetphonotypic-journalprimary-source-verificationhistory-of-linguistics

The Phonotypic Journal, "Conducted by I. Pitman" per its own masthead (itself printed in the Phonotypic Alphabet), carried "Completion of the Phonotypic Alphabet" in its June 1845 issue (Vol. 4, No. 42, p. 105): "It is with great pleasure we are now able to announce that our experiments upon the best forms that can be assigned to the Phonotypes have been brought to a satisfactory conclusion." The following issue (July 1845, No. 43, p. 121) carried "Extension of the Phonotypic Alphabet," adding symbols for foreign sounds and explicitly cross-referencing Ellis's Alphabet of Nature by page number as the companion analytical text (see claim-ellis-1845-alphabet-of-nature-describes-epa-letterforms-designed-conjointly-with-pitman).

This is Pitman's own publishing venue documenting the EPA's completion in his own editorial voice, independently corroborating the June/July 1845 dating already carried by claim-pitman-and-ellis-co-created-english-phonotypic-alphabet from Pitman's side of the collaboration.