It was a strangely worded line. Maybe, "Ahead full thrusters," or something like that. Maybe even shouting, "Ahead FULL THRUSTERS!"
Or no words at all, just an approving nod.
As far as Kirk having any kind of line like "engage," goes, he did say, "Take us home, Sulu," in the film. That's a line I can remember him using variations of more than once in TOS and the movies.
A lot of the time it was "Ahead Warp Factor [x]..."
I liked the intent of the line and the delivery, but they did need a better line, preferably a straight lift like:
"Thrusters ahead. Take us out."
"The word is given: warp speed!"
another nice one would have beeh:
"Second star to the right, and straight on 'till morning!"