If people want a connection to Luffy with Yamato before, you can always point to Yamatos making the Vivre Card for Ace and the words before they left hell Oda brought it up in the latest Magazine:
Aces line is the same from Yamato meaning it made an impact, Luffy heard Yamatos words two years before they meet, Oda pretty much said this in Magazine 13
@Garp the Fist
Yamato made the Vivre Card that kept not only themself connected to Ace, but Luffy and Ace connected all throughout Luffy journey, through Impel Down and through the War till Aces death.