Welcome to Steemit! You get paid for a post 7 days after you post it. Also you should be able to tap on the dollar amount next to the upvote to see when and how much you will get paid. I don't think there is a minimum. Half goes to steem dollars which you can turn into cash, the other half goes to steem power. I agree with claytonv, you should power up to gain more power and make more money
what if I want to withdraw to poloniex/bittrex ?