So I should rather say that Barbour was the first to come up with 606/607 as being the date for the destruction of Jerusalem by Nebuchadnezzar, with Russell close behind.
Yes, Barbour and his pal Paton were both proclaiming that 606 was the date when "...God gave all into the hands of Nebuchadnezzar" (And other such things) throughout the latter half of 1875.
Russell did not come into contact with Barbour's work until early in 1876 and by his own testimony, had rejected Adventist chronology and date setting up until that point.