What are the odds of early termination of unsupervised probation?

Part of the answer here probably depends on whether you have completed all the requirements of the program you're on, other than the time itself, such as attending classes or AA meetings or counseling, paying fees, etc.  If so, you might be able to get something done here.  I doubt that the probation can simply be dropped, because that minimum time is statutory and the people supervising you don't have the legal authority to ignore that or make an exception for you.

What you might be able to do, though, is get the rest of your supervision transferred to your new state.  I'd take whatever you have to show the new job offer to your supervising agency, and ask about that, and what would be involved.  I'd also suggest that you do this with the attitude that you're asking for a favor, for some help, because you don't have any right to a transfer; humility in your situation is often the best strategy.