At the end of the opening credits 'and Introducing Michael Caine' is shown, this would suggest that this was his first film. In fact MC had previously had five credited film roles, numerous TV appearances and several uncredited film roles before appearing in Zulu.
The title has fire within its letters, and it flies directly at the screen. Additionally, the title itself doesn't appear on screen until after the opening credits have finished rolling.
Opening credits prologue: JANUARY 23rd 1879
"And introducing Michael Caine"