It depends on your personal ambitions and goals. Where do you see yourself in five years from now?
It also depends on the company - is it reliable, do you trust them to keep a promise they have to fulfill in five years from now?
Most of all: How much do they pay you? At the end of the day, you're trying to earn a living with this job, or aren't you? (plenty of young "pilots" are not)
If you think of the whole thing as a career-progression, it is arguable how much it is worth in your CV to have 1500 hours command time on a turboprop (which you may get within two years).
- Many big airlines are only interested in jet-experience, so that would be an argument to stay on the jet, even if it is only as a First Officer.
- On the other hand, only Captains with some experience are really valuable to other airlines.
It's hard to give you solid advice as to what to do. I can only suggest to think about these points. The main question is, where do you want to go next.
I personally don't believe in the old "Never reject a command" - I know enough guys with thousands of hours on a King Air or Dash 7, who are unable to get a job on an A320.
There is no general rule.