Now that you have registered your Ethereum address with your newly created EOS public and private keys, you’ll need to go and look up your username that will be assigned to this address upon the genesis block of the EOS blockchain.

About this step, I didn't get EOS through the website but the Bitshares DEX (Open.EOS), then sent it to my ETH address in MEW, then used Register on the Contracts tab and Keys to confirm my public EOS key has been mapped to the smart contract "EOS Contribution". Is this last step only available when the snapshot takes place in early June? Or are snapshots being taken by the EOS website at the end of each ICO period?

Is there a way of finding a username other than the above link? I would think based upon Dan's previous projects that it could be user assigned just like Bitshares and Steemit do it.