Not quite, to be fair to the guitarists - mostly country players eg Bill Carson - who first played the Strat during its development and introduction in 1954. The player in Gene Vincent’s Blue Caps used one as well. But obviously none had the profile of Holly.
Good points. I went looking on the subject, and this is what I found:
“4. Buddy Holly was one of the first rock ‘n’ rollers to play a Stratocaster
Along with those glasses, a Fender Stratocaster was the other vital component part of Holly’s image. From Hank Marvin to Jimi Hendrix, so many would follow his lead over the following decades.”
So it merely says, ‘One of the first rock & rollers’, not that he introduced it. But as you mentioned, he was high profile, & probably set a trend.
http://www.musicradar.com/news/guitars/5-reasons-why-buddy-holly-is-still-cool-194609