Statistics of your workers are displayed as soon as they submit the first valid share to the pool. This can take several hours in case of CPU mining and several minutes in case of GPU mining. If you GPU mine and your worker is still not recognized by the pool check that your miner in fact submits shares to the pool (e.g. look out for messages like "share submitted" or similar) and that the shares are accepted by the pool (usually mining software print something like "Share accepted").