system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Trek] What was Kirk’s job before he became Captain?

I watched the 2009 remake recently and wondered what Kirk was doing at Starfleet before joining the Enterprise. Presumably everyone has to specialise in something and that becomes your job when you join a ship, you can’t just graduate in Captaincy. So what was he doing?

I can’t find any answers to this online (shockingly when you Google “Captain Kirk job” you don’t get much help) so I wondered if there was canon that I don’t know.
gpt
He didn't have a "job"; he was a student at Starfleet Academy. Because of the attack on Vulcan, all the cadets were mobilized and assigned as crew to Starships.

It's not clear what his precise "assigned" task was, but it was probably just "duties as assigned" which we can see exactly what he does.

He's "promoted" to First Officer, but that's not a rank, it's a position. He basically tricks Spock into stepping down which makes Kirk Captain, but - again - he's Captain as a position, not a rank (whoever is in commander of the ship is traditionally called "Captain").

After all of the shenanigans are done he's officially promoted to Captain.

Given all of the stuff he did the best description of his "job" between cadet and Captain would be "criminal."