I question this. We used this term regularly in the Smalltalk community at or before 1992.
But whatever. As Jan Steinman so aptly put it so many years ago:
"Java: All the speed of Smalltalk written in all the elegance of C"
In Self 1 and 2 we also used dynamic compilation and we got adaptive compilation in Self 3. This moved from Sun to Animorphic for the Strongtalk project and got bought by Sun to become the Java HotSpot technology.
JIT was very popular among Japanese car manufacturers and the term was borrowed for Java. Note that Java only had simple interpreters in its first few years so we are talking the late 1990s here.