You can't. Countries exist as sovereign entities only when it is infeasible for neighboring countries to invade and annex them. 1000 people is not enough to defend territory against any existing country, no matter how well-armed and well-fortified those 1000 people are, and the 200 people you'll maybe have after two months, even less so. If you are really good friends with the heads of state of all the neighboring countries, you might be able to get their approval and have a little bit longer to build up your strength. But you probably aren't, or you wouldn't be asking here, and even if you were you probably couldn't.
Who are the 1000 people? Why do you think they would move there?