Mining pools have some threshold under which they don't pay mining rewards. So you need to contribute until you have reached that threshold and, after that, they should send you your rewards. The threshold is there to avoid extra transactions (each transaction costs).
The time it takes to reach the reward threshold depends mostly on your hashrate. So the more you contribute, the faster you get your rewards. You can probably see your current contributions somewhere in the mining pool dashboard. The actual server you use shouldn't make much difference - the only other thing that may make a difference is the mining pool you choose: they have different thresholds and a bit different fee structure.