I'd probably to get entry-level/specialist job in Finland too and being paid for 3.000 € in a month gross.
You'd be lucky to get a third of that in Poland, and possibly only a quarter. Quite honestly, you don't seem to have any particular skills or experience that would make you attractive on the job market except, perhaps, for the fact that you speak Finnish, which is a wild card.
The reason why I consider Poland as my next move is to gain aforementioned experience and hopefully faster career progression.
It's hard for me to see how. Your time would be much better spent getting actual certification as an accountant in Finland, whether working full-time, part-time or not at all at the job you mentioned above. Or obtain some higher level certificate or degree that means something on the job market (according to real live people in your field that you know personally and have talked to face to face).
Come to Poland only if you can afford a year to totally goof off, totally or largely at your own expense, with little, if anything, in the way of return in terms of wages, savings, or professional advancement. Think of it as an extended vacation, and no more, and you won't be disappointed. If you expect anything more that fun, "adventure" and a possibly interesting experience, then you are likely to regret it.
Sorry, there's nothing in what you wrote that indicates that moving to Poland would be a wise career choice for you.
master in industrial management
Missed this on the first read. Criminy, another poor sucker with a useless degree who could have studied engineering instead. Business and management masters degrees are worthless without abundant prior serious experience, and unless they come from a top school. Shoot the dork who advised you to go for that degree. He (or she, to be fair) did you a great disservice.
You might want to consider reschooling yourself as an engineer. It's not to late at all, and you will greatly increase your salability on the job market, as well as your lifetime earnings and savings potential, especially if you get a degree in a highly paid field such as petroleum, geological or biomedical engineering. If you want to stay in the business/finance realm, then get a useful degree in something math-intensive like financial engineering, financial mathematics, econometrics or actuarial science.
Math is money.