to my knowledge there was an other show: January 1926, by J.L. Baird in the UK.
This is not posted to correct you, but rather to indicate we all are on thin ice when referring to `firstsī, especially with reference to technological advances, and especially their publication. (I got this show from a just acquired brochure, and thus by accident at hand: The EBU Review - 50 Years of Television, where I found this somewhere; there is no `firstī given.)
It would be interesting to know when he became influential in North America and when in Europe.
(Concerning what I said above, here one is less on thin ice but rather on water.)